Transmission system

ABSTRACT

Transmission systems are disclosed which include a dual sunwheel system having an output sunwheel ( 70 ) and a control sunwheel ( 80 ). A planet cage ( 18 ) is arranged around the dual sunwheel system and includes a planet gear ( 62 ) in mesh with the sunwheel ( 70 ) and a planet gear ( 64 ) in mesh with the sunwheel ( 80 ). The planet gears ( 62, 64 ) are coupled to one another. The drive ratio of the transmission is controlled by controlling the cage ( 18 ) or the control sunwheel ( 70 ). The speed of rotation of the input ( 22 ), output ( 20 ) and control sunwheel ( 70 ) are sensed by sensors ( 90 ) and control signals are generated to control a control device to thereby control the rotation of planet cage ( 18 ) or the control sunwheel ( 80 ) to thereby set the drive ratio of the transmission. The control devices can include a motor, one or more magnetic powder clutches, a variable centroid system and a mechanical pitch transfer gear system.

This invention relates to a transmission system and in particular to acontinuously variable transmission for continuously varying a driveratio of the transmission between a minimum value and a maximum value.The invention has particular application to systems including more thanone drive motor and, in particular, to both series and parallel hybridvehicles including an internal combustion engine and an electricpropulsion motor for powering the vehicle.

The invention provides a transmission system including:

a dual sunwheel system having a first sunwheel and a second sunwheel,the first sunwheel providing output rotary power when the transmissionsystem is operating;

a planet system including a first planet gear and a second planet gearcoupled to the first planet gear, the first planet gear meshing with thefirst sun gear and the second planet gear meshing with the second sungear;

a cage for carrying the planet system;

input means for receiving input power from an input power source andsupplying the input power to the dual sunwheel system to cause the dualsunwheel system to supply rotary power at the first sunwheel; and

control means for controlling the dual sunwheel system so as to set thedrive ratio of the transmission by causing the first sunwheel to advanceor regress relative to the input means by displacing momentum back andforth between the first sunwheel which provides the output rotary powerand the control means.

In one embodiment of the invention the input means comprises a shaftcoupled to the second sunwheel so that rotation of the second sunwheelcauses rotation of the planet system to in turn rotate the firstsunwheel.

In this embodiment of the invention the control means comprises the cageof the sunwheel and cage speed control means for rotating the cage tocause the first sunwheel to advance or regress relative to the secondsunwheel and change the drive ratio of the transmission.

In other embodiments of the invention the input means comprises theplanet cage of the dual sunwheel system and the control means includes acontrol shaft coupled to the second sunwheel for rotating the secondsunwheel to cause the first sunwheel to advance or regress relative tothe cage to change the drive ratio of the output relative to the cage.

In this embodiment of the invention the input to the cage may be from asingle power supply coupled directly to the cage.

However, in other embodiments a dual power supply system may beutilised. In this embodiment the cage of the sunwheel system is coupledto an epicyclic planet system, the epicyclic planet system having afirst input for input of power and a second input for input of power,the epicyclic planet system being connected to the cage of the dualsunwheel system to thereby rotate the cage to provide the input rotatorypower into the dual sunwheel system.

The epicyclic planet system includes an epicyclic sunwheel, an orbitgear and at least one said epicyclic planet gear, the said epicyclicplanet gear being carried by the cage of the dual sunwheel system, afirst input shaft connected to the epicyclic sunwheel and a second inputshaft connected to the orbit gear so that when either or both of thefirst or second input shafts is rotated the epicyclic planet gear orbitsabout the epicyclic sunwheel to thereby rotate the cage of the dualsunwheel system and provide input rotary power into the dual sunwheelsystem.

The provision of the epicyclic planet system in this embodiment of theinvention provides a decoupling of the two input power supplies so thateach can remain connected into the system and each can operateindependently of the other or jointly with the other without interferingwith the operation of the other power supply.

In general, transmission systems for hybrid vehicles or otherenvironments in which more than one input supply is used, require anuncoupling of one of the power supplies at some stage when the other ofthe power supplies is driving the system. This uncoupling is usuallyperformed by a clutch, mechanical dog or other device. The need toprovide this uncoupling can result in waste of energy and alsoadditional mechanical components which are required in the system.

It would therefore be desirable to provide a transmission system inwhich the inputs can be decoupled, that is they remain in drivingcontact with the transmission but each is able to drive independently ofthe other without effecting the operation of the other.

This aspect of the invention relates to a transmission system which hasa plurality of input power supplies.

This aspect of the invention provides a transmission system including:

an epicyclic planet system having an orbit gear, a sunwheel and at leastone planet gear between the sunwheel and the orbit gear, the orbit gearreceiving input rotary power from a first power source and the sunwheelreceiving input rotary power from a second power source;

a dual sunwheel system having a first sunwheel and a second sunwheel,the first sunwheel being coupled to an output shaft;

the dual sunwheel system further having a planet system including afirst planet gear in mesh with the first sunwheel and the second planetgear in mesh with the second sunwheel, the first and second planet gearsbeing coupled together, the planet system being supported in a cage, thecage also carrying the at least one planet gear of the epicyclic planetsystem so that when input rotary power is input from the first or secondsource to the orbit gear or the sunwheel of the epicyclic planet systemthe planet gear of the epicyclic system orbits about the sunwheel of theepicyclic planet system to rotate the cage and thereby supply rotarypower to the planet system and to the first sunwheel to drive theoutput; and

a control means coupled to the second sunwheel for controlling therotary speed of the second sunwheel which in turn rotates the planetsystem via the second planet gear to cause the first sunwheel to advanceor regress relative to the cage to thereby change the drive ratio of thetransmission.

Preferably the control means includes:

a control circuit having at least a first sensor and a second sensor forproviding respective signals indicative of the rotary speed of any twoof the cage, the second sunwheel and the output, and processingcircuitry for receiving the signals and for producing a control signal;and

a control mechanism for driving or impeding rotary motion of the secondsunwheel dependant on the control signal.

In one embodiment of the invention, the first and second sensors sensethe speed of the cage and the output respectively. However, in anotherembodiment, the sensors detect the speed of the cage and the secondsunwheel, and the speed of the second sunwheel is used as an indicativespeed of the output.

In one embodiment of the invention the control mechanism comprises anelectric motor. However, in another embodiment of the invention thecontrol mechanism comprises a magnetic powder brake or clutch.

In yet in further embodiments the control mechanism may comprise amechanical or hydraulic variable drive.

In embodiments where the electric motor is utilised, the motor usesenergy to control the control shaft. That energy is returned to thesystem as momentum or drive. When the control motor is impeding rotationof the control shaft so as to control the drive ratio of thetransmission energy is extracted from the system in the form ofelectrical power which, can be used to power other electric componentsor to recharge batteries.

If mechanical or hydraulic control systems are utilised those systemsmay not be as efficient as embodiments in which an electric motor isused. In these embodiments some energy may be put back into the systemand some energy will be lost.

Preferably the processing circuitry includes:

means for setting a predetermined ratio between the first and secondsignals and for producing an initial control signal indicative of avariation from the set ratio;

means for producing the control signal in the form of a variable pulsesignal having a duty cycle indicative of the magnitude of the initialcontrol signal; and

switch means for receiving the variable pulse signal, the switch meansbeing coupled in a power supply to the control mechanism so that thecontrol mechanism is powered by switching the switching means on by thevariable pulse signal so that the control means is powered on in pulsefashion with a duty cycle dependant on the duty cycle of the controlsignal so the control shaft is driven to increase rotary speed when thecontrol mechanism is powered and impedes rotation on the control shaftwhen the control mechanism is not powered is set in accordance with theduty cycle of the control signal.

In embodiments where the control mechanism is a motor the motor speed isdependant on whether the motor is being driven, that is powered, or isnot being driven. The faster the control shaft is moving, the highergear the transmission is in (that is the lower the gear ratio). If themotor is switched on and powered it can supply drive to the controlshaft to increase its speed thereby reducing the gear ratio. If themotor is not powered then the control shaft can slow down therebyincreasing the gear ratio. Thus by continually comparing the initialcontrol signal with a predetermined value such as 0 volts, the motor canbe switched on or off to either increase the speed of the control shaftor allow the control shaft to slow so as to produce an initial controlsignal which is indicative of 0 volts or 0 error voltage from the presetlevel. When 0 volts is produced the controls shaft is rotating at therequired speed to provide the required drive ratio and therefore themotor need not be operated. Thus, the motor is continually switched onor off to attempt to achieve an initial control voltage of that 0voltage. In embodiments where a magnetic clutch or brake is utilised theamount of progressive braking supplied by the clutch is alsoproportional to the pulse width of the control signal so that the speedof the second sunwheel can be increased or decreased by the magneticbrake or clutch.

Preferably the switching means comprises at least one transistor whichis provided in series with the control mechanism so that when thetransistor is switched on power is able to flow through the controlmechanism to activate the control mechanism to increase the rotationalspeed of the second sunwheel.

In one embodiment the control mechanism is a motor, and a secondtransistor is arranged in parallel with the motor so that when the firsttransistor is switched off, the second transistor is switched on andcurrent is able to flow through the second transistor and to a load sothat in environments in which the motor is running at a speed higherthan the input power to the motor the motor can generate electricity andsupply that electricity to the load and impede the rotation of thecontrol shaft.

In some embodiments of the invention the load may comprise a battery forsupplying power to an electric propulsion motor in a hybrid power supplysystem so that the motor can recharge the batteries depending upon theoperating conditions of the motor.

Preferably the control circuity includes current sensing means forsensing current supply to the motor and, in the event of over supply ofcurrent, switching off the switching means so that current cannot flowthrough the motor and the motor is de-energised.

Preferably the control circuitry also includes a reverse gear signalindicating means for providing a reverse signal when the transmissionsystem is placed in reverse for preventing the switching means fromswitching on so as to maintain the motor in a switched off conditionwhen the vehicle is in reverse gear.

The invention may also be said to reside in a transmission systemincluding:

a dual sunwheel system including a first sunwheel provided on an outputshaft for supplying output rotary power;

a second sunwheel;

a control shaft coupled to the second sunwheel;

a planet system having at least a first planet gear in mesh with thefirst sunwheel and a second planet gear in mesh with the secondsunwheel;

a cage for carrying the planet system;

input rotary power supply means for supplying input rotary power to thecage; and

control means for controlling the speed of rotation of the control shaftto control the speed of rotation of the second sunwheel to set the driveratio of the transmission.

Preferably the control means comprises a control motor for controllingrotation of the control shaft.

In another embodiment of the invention the control means comprises afirst magnetic powder clutch having a first component including a coiland a second component including a brake element, the first componentbeing coupled to either the cage or the control shaft, and the secondcomponent being coupled to the other of the cage or the control shaft sothe component which is coupled to the cage rotates with the cage uponsupply of input rotary power to the transmission system, and controlpower supply means for supplying a control signal to enable energisationof the coil to cause the magnetic clutch to activate so as toprogressively lock the component having the coil to the component havingthe brake element so that rotation is transmitted from the componentcoupled to the cage to the component coupled to the control shaft tothereby make the control shaft rotate in accordance with the controlsignal supplied to the coil.

In this embodiment of the invention a second magnetic powder clutch ofthe same structure as the first magnetic clutch is also provided, thesecond magnetic clutch having its first component fixed stationary andits second component coupled to the control shaft so that when a controlsignal is supplied to energise the second magnetic clutch the secondmagnetic clutch can completely lock-up to prevent rotation of thecontrol shaft to thereby cause the control shaft to remain stationaryand thereby place the transmission system into reverse gear.

In accordance with this embodiment of the invention in order to provideprecise ratio control of the transmission both the first and secondmagnetic clutches can be controlled with control signals from acontroller to precisely adjust the speed of rotation of the controlshaft to precisely set the drive ratio of the transmission.

Preferably the first magnetic clutch has the first component includingthe coil coupled to the cage for rotation with the cage, the firstcomponent including a slip ring for engaging a ring fixed stationary inthe transmission system so control signals can be supplied via the fixedring to the slip ring and to the coil in the first component.

In one embodiment of the invention the planet system comprises the firstplanet gear and the second planet gear fixed integral with the firstplanet gear, the integral first and second planet gears being mounted ona shaft fixed to the cage.

In other embodiments the planet system comprises the first planet gearin mesh with the first sunwheel, the second planet gear being separatefrom the first planet gear and in mesh with the second sunwheel, and thefirst and second planet gears being coupled by an idler gear in meshwith both the first and second planet gears.

In a still further embodiment the planet system comprises the firstplanet gear in mesh with the first sunwheel, and the second planet gearbeing in mesh with the second sunwheel and being coupled in the firstplanet gear by being in mesh with the first planet gear.

In a still further embodiment of the invention the planet systemcomprises the first planet gear in mesh with the first sunwheel, thesecond planet gear in mesh with the second sunwheel, and an idler planetgear fixed onto the second planet gear for rotation with the secondplanet gear and the idler gear being in mesh with the first planet gearto thereby couple the first planet gear to the second planet gear.

A still further aspect of the invention may be said to reside in atransmission system including:

a dual sunwheel system including a first sunwheel provided on an outputshaft for supplying output rotary power, a second sunwheel, a planetsystem having at least a first planet gear in mesh with the firstsunwheel and a second planet gear in mesh with the second sunwheel, thefirst and second planet gears being coupled together, a cage forcarrying the planet system;

input rotary power supply means for supplying input rotary power to thedual sunwheel system;

a first magnetic powdered clutch having a first component including acoil and a second component including a brake element, the firstcomponent being coupled to the dual sunwheel system for controlling thedrive ratio of the transmission system or an input drive control, andthe second component being coupled to the other of the dual sunwheelsystem or the input drive control;

a second magnetic powdered clutch having a first component including acoil and a second component including a brake element, the firstcomponent being coupled to either the dual sunwheel system or being heldfixed stationary, and the second component being coupled to the other ofthe dual sunwheel system or fixed stationary; and

power supply means for supplying power to the first and second magneticpowder clutches to control the dual sunwheel system to thereby set thedrive ratio of the transmission system.

According to this aspect of the invention by controlling the firstmagnetic clutch preliminary or primary control over the dual sunwheelsystem is obtained in order to set the drive ratio of the transmissionand precise control an more rapid adjustment to a particular ratio canbe set by activating the second magnetic clutch which can quicklycorrect for any over adjustment produced by the first magnetic clutch tothereby set the drive ratio of the transmission system accurately andquickly in response to the environment in which the transmission isoperating.

In the preferred embodiment of the invention the input drive controlcomprises the input rotary power supply means so that the input rotarypower into the transmission drives the first or second component of thefirst magnetic clutch so that when the clutch is activated the degree ofslippage between the first and second component is changed to cause theother of the first or second component to move with a particular degreeof slippage with respect to the first component so as to control thedual sunwheel system to set the drive ratio of the transmission, andwherein additional control is effected by operating the second magneticclutch so as to cause the first or second component of the secondmagnetic clutch to further control the dual sunwheel system to set thedrive ratio of the transmission.

Preferably the first component or second component of the first andsecond magnetic clutches is connected to the second sunwheel of the dualsunwheel system for controlling the drive ratio of the transmission.

Preferably the second sunwheel includes a control shaft and the first orsecond component of the magnetic clutches is connected to the controlshaft.

Preferably the second component of the first and second magneticclutches is connected to the control shaft.

Preferably the first component of the first magnetic clutch is connectedto the cage for carrying the planet system so that when the cagerotates, the first component of the first magnetic clutch rotates withthe cage, and when the first magnetic clutch is operated to produce thedesired degree of slippage between the first and second components thesecond component is caused to rotate in accordance with a degree ofslippage of the first magnetic clutch.

The invention also provides a controller for controlling a ratio controldevice for setting a drive ratio of a transmission system, saidcontroller including:

sensor means for providing first and second speed signals indicative ofthe rotary speed of any two of the input power supply into thetransmission system, the rotary speed of a ratio control member whichsets the drive ratio of the transmission, and the output shaft;

ratio adjusting means for setting an adjustment ratio and for providingan output signal if the ratio of first and second speed signals differsfrom the adjustment ratio;

control signal generating means for generating a control signaldependant on the output signal; and

switching means for receiving the control signal and for controlling theratio control device to cause the control device to drive the ratiocontrol member to thereby set the drive ratio of the transmission.

Preferably the sensor means provides first and second speed signalsindicative of the input power supply and the output shaft.

However, in other embodiments, the sensor means for providing the firstand second speed signals can provide speed signals of the input and theratio control member, with the speed of the ratio control member beingused as an indicative speed of the output shaft.

Preferably the ratio adjusting means comprises a voltage divider pot forreceiving the first and second speed signals and outputting the outputsignal if the ratio of the voltage of the first signal to the voltage ofthe second signal is different to the ratio set by the voltage divider.

Preferably the control signal generating means includes a pair ofoperational amplifiers, the amplifiers each receiving a saw tooth wavesignal and an offset signal, the offset signals being of differentmagnitude and the output of the operational amplifiers being a variablepulse width signal, set in accordance with the magnitude of the outputsignal, which provides said control signal.

Preferably the operational amplifiers are coupled to the switching meansfor controlling the switching means to enable the switching means toswitch power supply to the control device so that the control device isoperated in accordance with the duty cycle of the variable pulse widthsignal supplied to the switching means.

In one embodiment of the invention the switching means comprises a firsttransistor connected in series with the control device so the each timethe transistor is switched on for a period set by the duty cycle of thecontrol signal the motor is powered on for periods set the duty cycle ofthe control signal.

In the embodiment which includes a control device in the form of amotor, a second switching transistor is also provided for enabling themotor to generate electricity in some operational conditions of thetransmission system and supply the generated electricity to a load. Inthis embodiment the first transistor is switched off when the secondtransistor is switched on so that motor is connected to the load forsupply of the electricity to the load and cause the rotation of thecontrol shaft to be impeded to rotate the motor in a state of constantspeed regardless of changing momentum condition in the transmissionsystem.

In some embodiments of the invention the load may be a battery and thesupply of electricity can be used to recharge the battery.

Preferably the controller also includes an overcurrent sensing means forsensing the supply of overcurrent to the motor and for causing the motorto be switched off to prevent damage to the motor.

Preferably the motor is caused to be switched off by the supply of asignal which prevents the first transistor from switching on to enablepower to be supplied through the motor to operate the motor.

Preferably the controller also includes a reverse signal generator forproviding a signal when the transmission system is placed in reversegear for preventing switching on of the first transistor to also preventthe motor from being energised by the supply of power to the motor.

Preferably the sensors comprise sensing circuitry which provides a firstvoltage signal which is a voltage signal proportional to the speed ofthe input and a second voltage signal which is proportional to the speedof the control member.

In one embodiment of the invention the sensor may include chopper wheelsconnected to the input and the control member, and photo-interruptersfor generating pulses when the chopper wheels rotate with the input andthe control member, the pulses producing frequency signals which areconverted into voltage signals proportional to the frequency andtherefore proportional to the rotary speed of the input and the controlmember.

The invention may also be said to reside in a transmission systemincluding:

a first sunwheel;

an output connected to the first sunwheel for providing output rotarypower;

a control sunwheel;

a planet system including a planet cage having first and second planetgears, the first planet gear meshing with the first sunwheel and thesecond planet gear meshing with the control sunwheel;

input supply means for supplying input to the planet cage so that rotarypower is transmitted from the cage via the first and second planet gearsto the first sunwheel and therefore to the output;

a controller for:

-   -   (a) receiving signals indicative of the rotary speed of at least        any two of the output, the control sunwheel and the input supply        means, and for producing control signals based on the said at        least any two of the speeds of the output, the control sunwheel        and the input supply means, to enable a change in drive ratio in        a forward direction of the transmission; and    -   (b) producing a locking signal when reverse motion of the        transmission is required;

a first progressive control device for receiving the control signalsfrom the controller to speed up or slow down the control sunwheelbetween a stationary condition of the sunwheel and a first rotary speedof the sunwheel to change the drive ratio of the transmission; and

a second control device for receiving the locking signal from thecontroller for locking the sunwheel to the input to increase the speedof rotation of the control sunwheel to a speed above the first speed tothereby place the transmission into reverse.

Preferably the first control device comprises a magnetic powder clutch.

Preferably the second control device comprises a cone clutch.

Preferably the sunwheel is provided on a control shaft and the controlshaft carries a gear which meshes with a gear coupled to an output ofthe first device and also with a gear coupled to an output of the secondcontrol device.

Preferably the controller includes a processor for receiving signalsindicative of the speed of the input supply means and the speed of theoutput, switching means connected to the processor for receiving outputsignals from the processor to switch the switching means on and off toproduce control signals for application to the first progressive controldevice for actuating the first progressive control device to speed up orslow down the control sunwheel.

Preferably the control signals comprise:

a DC pulse signal for actuating the first progressive control device tolock the first progressive control device to the control sunwheel;

a variable AC frequency signal for controlling the first progressivecontrol device to adjust the speed of the control sunwheel to a speedless than the said first speed; and

a variable pulse width AC signal for actuating the first progressivecontrol device to enable the control device to control the speed of thecontrol sunwheel from the said certain speed to the first speed.

Preferably the controller includes means for producing a transitionAC/DC signal for transition of the control signal from the DC pulsesignal to the AC variable frequency signal.

The invention may also be said to reside in a transmission systemincluding:

a first sunwheel;

an output connected to the first sunwheel for providing output rotarypower;

a control sunwheel;

a planet system including a planet cage having first and second planetgears, the first gear meshing with the first sunwheel and the secondplanet gear meshing with the control sunwheel;

input supply means for supplying input rotary power to the planet cageso the rotary power is transmitted from the cage via the first andsecond planet gears to the first sunwheel and therefore to the output;

a controller including speed indicating means for providing signalsindicative of the rotary speed of at least any two of the output, thecontrol sunwheel and the input supply means, and for generating acontrol signal for controlling the drive ratio of the transmissionsystem; and

a control mechanism for receiving the control signal and for controllingthe control sunwheel in accordance with the control signal to therebyadjust the drive ratio of the transmission.

In one embodiment the control device includes a first progressivecontrol device for receiving the control signal from the controller tospeed up or slow down the control sunwheel to change the drive ratio ofthe transmission.

In this embodiment the control device may also include a second controldevice, the controller also being for generating a locking signalindicative of the requirement for reverse gear, the second controldevice being for receiving the locking signal and for causing the secondcontrol device to lock the control sunwheel to the input to increase thespeed of rotation of the control sunwheel to a speed above the firstspeed to thereby place the transmission into reverse gear.

Preferably the first control device comprises a magnetic powder clutch.

In one embodiment of the invention the control sunwheel is connected toa control shaft which comprises a first control shaft portion and asecond separate control shaft portion, the first and second controlshaft portions being coupled together by gears, the control mechanismbeing mounted on the second control shaft portion.

In one embodiment of the invention the control device is mounted forrotation and is coupled to control shaft drive means for rotating thecontrol mechanism.

Preferably the control shaft drive means comprises a gear system whichtransmits drive from the input to the control device.

Preferably the gear system comprises a ring gear coupled to the cage, apinion gear meshing with the ring gear, a shaft coupled to the piniongear, a second pinion gear on the shaft, a second ring gear havinginternal and external teeth, the second pinion meshing with the internalteeth, and the external teeth meshing with a gear coupled to the controldevice for rotating the control device.

Preferably the control device comprises a magnetic powder clutch havingan outer housing portion coupled to the further gear, and an innersection mounted on the second portion of the control shaft, so that whenthe input is driven, the outer housing of the powder clutch is rotatedby the gear system and when the powder clutch is activated, the innersection and second portion of the control shaft is controlled inrotation, dependent on the control signal supplied to the powder clutchto in turn control the rotation of the first portion of the controlshaft and therefore the control sunwheel, to set the drive ratio of thetransmission.

In a still further embodiment of the invention the second portion of thecontrol shaft includes a variable centroid system having moveable masseswhich, upon rotation of the second portion of the control shaft, moverotary outwardly to slow down rotation of the second portion of thecontrol shaft and therefore the first portion of the control shaft.

In a still further embodiment the control device includes a firstvariator having a toroidal gear track having gear teeth which change inpitch from an inner diameter portion to an outer diameter portion, thefirst variator being coupled to a variator drive mechanism for rotatingthe first variator, a second variator having a toroidal track havinggear teeth which change in pitch from an inner diameter portion to anouter diameter portion, the second variator being connected to thecontrol shaft, a pitch transfer gear in mesh with the gear teeth of thefirst variator and the gear teeth of the second variator, means forrotating the pitch transfer gear so that the gear can engage at anyportion along the variable pitch of the toroidal track of the firstvariator and the toroidal track of the second variator to thereby set adrive ratio between the first and second variators, and a driver forsetting the orientation of the pitch transfer gear.

Preferably the variator drive system comprises a gear system fortransmitting drive from the input cage to the first variator.

Preferably the control shaft comprises a first control shaft portion anda second control shaft portion, a pair of gears for coupling the firstcontrol shaft portion to the second control shaft portion, the firstvariator being rotatable relative to the second control shaft portionand the second variator being mounted on the second control shaftportion for rotating the second control shaft portion so that the secondcontrol shaft portion and therefore the first control shaft portion iscontrolled in rotation, dependent on the gear ratio set by the pitchtransfer gear.

Preferably the orientation of the pitch transfer gear is set by astepper motor and the stepper motor receives the control signal toactivate the stepper motor to rotate the stepper motor to in turn changethe position of the pitch transfer gear to control the rotation of thecontrol shaft and therefore the control sunwheel.

Preferred embodiments of the invention will be described, by way ofexample, with reference to the accompanying drawing in which:

FIG. 1 is a schematic diagram of a transmission system according to afirst embodiment of the invention;

FIG. 2 is a schematic diagram of a transmission system according to asecond embodiment of the invention;

FIG. 3 is a cross-sectional view through part of the transmission systemof FIG. 1;

FIG. 4 is a schematic view of a modified form of the system shown inFIG. 2;

FIG. 5 is a cross-sectional view through part of the embodiment of FIG.4;

FIG. 6 is a cross-sectional view of a transmission system according to astill further embodiment of the invention;

FIGS. 7, 8 and 9 are views showing various dual sunwheel systems whichare used in the embodiments of the invention;

FIG. 10 is a circuit diagram forming part of a control system used inthe preferred embodiments of the invention;

FIG. 11 is a further circuit diagram showing the remainder of thecontrol system used in the preferred embodiment of the invention;

FIG. 12 is a diagram showing an operational amplifier used in thecircuit of FIG. 11 and used to illustrate operation of that circuit;

FIG. 13 shows how pulse width control is performed by the circuit ofFIG. 11 in order to control the drive ratio of the transmissionsaccording to the preferred embodiments of the invention;

FIGS. 14, 15, 16, 17, 18 and 19 are diagrams showing signals created andused in the circuit of FIG. 11 to facilitate explanation of the mannerin which the circuit operates;

FIG. 20 is a circuit diagram similar to FIG. 19, showing a furtherembodiment of the invention;

FIG. 21 is a graph which explains the control of the control shaft andthe manner in which momentum is switched to displace momentum from onepart of the transmission to another part of the transmission;

FIG. 22 is a cross-sectional view of a still further embodiment of theinvention which operates in accordance with the principles describedwith reference to FIG. 21;

FIG. 23 is a perspective view of the embodiment of FIG. 22 with some ofthe parts removed for ease of illustration;

FIG. 24 is a block circuit diagram of a second controller according toanother embodiment of the invention which has particular application tothe embodiment of FIGS. 22 and 23;

FIG. 25 is a diagram of a further section of the controller according tothe second embodiment;

FIGS. 26, 27, 28, 29 and 30 are wave form diagrams which will be used toexplain the embodiment of FIGS. 24 and 25;

FIG. 31 is a simplified circuit diagram of part of the circuit of FIG.25 used to facilitate explanation of the wave form diagrams of FIGS. 26to 30;

FIG. 32 is a graph illustrating the transmitted torque v 1/impedance ofa powder clutch used in the embodiment of FIGS. 22 and 23, also used toexplain the operation of FIGS. 26 to 31;

FIG. 33 shows a further embodiment which is a modification to theembodiment described with reference to FIG. 22;

FIG. 34 shows a still further modification to the embodiment of FIG. 33;

FIG. 35 is still a further embodiment of the invention which shows adifferent modification to the embodiment of FIG. 22; and

FIG. 36 is a perspective view of the embodiment of FIG. 35 from theexterior of the transmission casing.

With reference to FIG. 1 a transmission system for a hybrid drive for amotor vehicle is disclosed. The hybrid drive of the motor vehicleincludes an internal combustion engine 12 and an electric propulsionmotor 14. One of the other motors 12 or 14 or both of the motors 12 or14 can be used to provide power to drive a vehicle.

The transmission system of this embodiment of the invention includes anepicyclic planet system 16 and a dual sunwheel transmission 18. The dualsunwheel transmission 18 drives an output 20.

The internal combustion motor 12 and the electric propulsion motor 14provide first and second inputs into the epicyclic planet system 16. Theinput from the motor 12 is via a first input shaft 22 into the epicyclicplanet system 16 and the input from the electric propulsion motor 14 isvia a belt 24 to a second shaft 26 of the epicyclic planet system 16.The input shafts 22 and 26 will be described in more detail withreference to FIG. 3.

In the embodiment shown in FIG. 1 the drive from the propulsion motor 14is via the belt 24. However, in production embodiments the electricpropulsion motor 14 can be directly mounted on the shaft 26 so that itsurrounds the shaft 26 and drives the shaft 26 directly without the needof a belt 24 to transmit the drive.

The transmission system of FIG. 1 also includes a control motor 28 whichcontrols rotation of a control shaft 30 of the dual sunwheel system 18.Drive is transmitted from the control motor 28 to the shaft 30 via abelt 32. However, once again, the control motor 28 can be mounteddirectly on the shaft 30 so that drive is transmitted directly to theshaft 30 without the need for a belt 32.

In the embodiment of FIG. 1 drive from either the motor 12 or the motor14, or drive from both the motors 12 and 14 is input into the epicyclicplanet system 16 which in turn drives the dual sunwheel system 18.Output power is supplied from the sunwheel system 18 to the shaft 20 toprovide output propulsion. The drive ratio of the transmission iscontrolled by rotating the control shaft 30 relative to the input intothe dual sunwheel transmission 18 by appropriate control of the controlmotor 28 as will be described in more detail hereinafter.

The coupling of the internal combustion motor 12 and electric propulsionmotor 14 to the dual sunwheel system 18 via the epicyclic planet system16 provides a decoupled connection of the two motors into thetransmission which means that each can function independently exceptthat they are part of the same planetary system and will alter the ratioat which power is input into the transmission. That is, if one motorshuts down the other is asked to supply sufficient power to drive thewhole system and is able to do this because the decoupling causes ahigher ratio for the motor left driving. Thus, the decoupling of thesystem by the epicyclic planet system enables both motors to be alwaysconnected to the system and either one or the other or both are able toprovide drive without the need to disconnect one motor from the systemsuch as by a clutch, dog or other mechanical device which wouldtherefore uncouple one of the motors from the system when it is notrequired to drive.

In the embodiment of FIG. 1 the control motor 28 is controlled tocontrol the control shaft 30 to set the drive ratio of the transmission.However, in some operating conditions the control motor 28 can also actas a generator to supply electricity. This supply of electricity can beused to recharge batteries (not shown) which power the electricpropulsion motor 14.

FIG. 2 shows a transmission system according to a second embodiment ofthe invention. In this embodiment only a single drive motor such as aninternal combustion motor 12 is utilised. The internal combustion motor12 is connected to an input shaft 27 coupled to a planet case 42 (seeFIG. 5) the sunwheel transmission system 18, and the sunwheel system hasa control shaft 30 which is controlled by a control motor 28 via a belt32 in the same manner as the previous embodiment. Once again, outputpower is supplied to output shaft 20 for driving a vehicle or othermachine.

FIG. 3 is cross-sectional view through the transmission system used inthe embodiment of FIG. 1. With reference to FIG. 3 input shaft 22 frommotor 12 is connected to a sunwheel 35 of the epicyclic planet system16. The second input shaft 26 is connected to planet cage 36 of thesystem 16. Planet cage 36 carries an orbit gear 38 which has internalteeth 40. A plurality of planet gears 38 (only one shown) mesh withteeth 39 of the sunwheel 35 and also teeth 40 of the gear 38. The planetgears 38 are journalled on shafts 40 which are fixed to a planet cage 42of the dual sunwheel system 18.

As shown in FIG. 3 the shaft 26 is concentric with the shaft 22 and inorder to provide relative rotation between the shaft 22 bearings orbushes 44 are provided between the shaft 22 and 26. The shaft 26 mayalso be mounted on an external bearing 45. Planet cage 36 of theepicyclic system 16 is mounted on the planet cage 42 via bearing 49. Thecage 42 of the dual sunwheel system 18 is mounted on a stub end 50 ofinput shaft 22 via a bearing 53.

Thus, when input drive is supplied to either the input shaft 22 or theinput shaft 26 or both the input shafts 22 and 26 that drive istransmitted to planet cage 42 of the dual sunwheel system 18 via, in thecase of the shaft 26, the planet cage 36, the gear 37, the planet gear38 and the shaft 40 which connects to the planet cage 42 to thereforedrive the planet cage 42, and in the case of the input shaft 22 via thesunwheel 35, the planet gear 38 and therefore the shaft 40 to drive theplanet cage 42. That is, in both arrangements the orbiting of the planetgears 38 about the sunwheel 35 will carry with them the cage 42 so thatthe cage 42 is rotated about the longitudinal axis of the input shaft 22and 26.

The cage 42 carries a plurality of planet systems 60. In the embodimentsshown in FIG. 3 the planet systems 60 are in the form of a planetcluster having a first planet gear 62 and a smaller planet gear 64formed integral with the planet gear 62. The integral cluster 60 ismounted on a shaft 66 which is fixed in the planet cage 42. In otherembodiments, as will be described with reference to FIGS. 7 to 9 theplanet system 60 can take forms other than an integral planet cluster ofthe type shown in FIG. 3.

The dual sunwheel system 18 includes a first sunwheel 70 and a secondsunwheel 80. The second sunwheel 80 is formed integral with the controlshaft 30. The first sunwheel 70 is formed on the output shaft 20. Thefirst sunwheel 70 has teeth 72 which are in mesh with teeth 68 on theplanet gear 62 and the second sunwheel 80 has teeth 82 which are in meshwith teeth 69 on the second planet gear 64.

As is shown in FIG. 3 the cage 42 is mounted onto the control shaft 30by a bearing 88 and the cage 42 has a bearing 90 which mount onto acasing (not shown) of the transmission. As seen in FIG. 3 the controlshaft 30 is mounted onto the output shaft 20 via bearings or bushes 81so as to allow for relative rotation between the shafts 20 and 30.

When the planet cage 42 is rotated due to input power supply to theshafts 22 and 26 the planet cluster 60 is carried with the cage 42.Because of the meshing of the gear 62 with the sunwheel 70 drive istransmitted to the sunwheel 70 to rotate the sunwheel 70 and thereforerotate the output shaft 20 to provide output rotary power from thetransmission. In order to control the drive ratio of the transmissionthe control shaft 30 is controlled by the control motor 28 describedwith reference to FIG. 1 so as to rotate the control shaft 30 at apredetermined speed relative to the input cage 42. By changing the speedof rotation of the control shaft 30 relative to the input cage 42 thespeed of rotation of the sunwheel 80 is also changed relative to thecage 42. Because of the meshing of the sunwheel 80 with the planet gear64 and integral coupling of the planet gear 64 with the gear 62 a changein relative speed of the sunwheel 80 will cause the planet cluster 60 toadvance or regress relative to the cage 42 thereby causing the speed ofthe sunwheel 70 to advance or regress to thereby change the speed of thesunwheel relative to the cage 42 and change the speed of the outputshaft 20 relative to the input shafts 22 and/or 26.

In order to control the drive ratio of the transmission the speed ofrotation of the input cage 42 relative to the control shaft 30 or output20 needs to be known so that the control shaft 30 can be controlledrelative to the speed of the input cage 42 and output shaft 20 to setthe drive ratio. In order to provide data for the relative control ofthe shaft 30 with respect to the input cage 42, the input cage 42,output shaft 20, and the control shaft 30 carry a slotted chopper wheel90. The wheel 90 rotate with the cage 42, shaft 20 or the shaft 30 asthe case may be and each of the wheel 90 has a photo-interrupter 92associated with it. As each slot (not shown) in the wheels 92 passthrough the respective photo-interrupter 92 a light pulse is detectedwithin the photo-interrupter 92 to provide data relating to the speed ofrotation of the shafts 20,30 and also the input cage 42.

In other embodiments rather than use a chopper wheel and optocoupler,other devices for providing data relating to the speed of rotation ofthe shafts 20 or 30 and the cage 42 can be used such as encoders and thelike.

The manner in which the speed of the control shaft 30 and input cage 42is monitored and used to control the drive ratio of the transmissionwill be described in more detail with reference to FIGS. 10 and 11.

In the embodiment of FIG. 3, if the control shaft 30 is rotating at thesame speed as the input cage 42 then drive ratio set by the transmissionis 1:1. If the control shaft 30 is rotating at speed slower than theinput cage 42 then the drive ratio will drop from 1:1 down towardsneutral depending on the speed differential between the control shaft 30and the input cage 42. If the control shaft is completely stopped theoutput shaft 20 will be caused to turn in the reverse direction therebyproviding a reverse gear. If the speed of the control shaft is greaterthan the input cage 42 then the drive ratio will go into overdrive.

Thus, by controlling the speed of the control shaft 30 via the controlmotor 28 the drive ratio of the system can be set.

FIG. 4 is a view of a modified form of the second embodiment describedwith reference to FIG. 2. In this embodiment rather than utilise controlmotor 28 in order to control the drive ratio of the transmission thedrive ratio is controlled by a magnetic clutch or brake system 110. Themagnetic clutch or brake system 110 provides a progressive braking forceto the control shaft 30 to adjust its speed. Such clutches are known andtherefore need not be described in detail.

In this embodiment of the invention a second magnetic clutch 120 whichcan be identical to the first clutch is mounted on a shaft 122 which iscoupled to the control shaft 30 by a belt 124. The purpose of the secondclutch 120 is to provide a reverse gear. This system incorporateselectric ratio control system 124 for supplying power to the clutch 110to cause the progressive braking so that the shaft 30 is driven at theprescribed speed and an electronic reverse control 126 which providespower to the clutch 120 to provide the reverse gear function.

As explained-with reference to FIG. 2 this embodiment of the inventionincludes a single drive motor such as an IC motor 12.

FIG. 5 is a cross-sectional view through the transmission system of FIG.4. Input supply is provided from the motor 12 to the input shaft 22which is coupled to first planet cage 42. Planet cluster 60 is mountedin cage 42 and, as in the earlier embodiment, planet gear 62 meshes withthe sunwheel 70 which is fixed onto the output shaft 20. Second sunwheel80 is mounted on the control shaft 30 as in the earlier embodiment and,in this embodiment the output shaft 20 can extend through the controlshaft 30 simply so that output power can be taken from either end of thetransmission shown in FIG. 5.

As in the earlier embodiment planet cluster 60 is fixed to the cage 42and the first planet gear 62 meshes with the sunwheel 70 and the secondplanet gear 64 meshes with the sunwheel 80. The first magnetic clutch110 has a housing 120 which includes a sleeve section 123 which is fixedto cage 42. The housing 120 is mounted on bearings 126 for rotationrelative to the control shaft 30. The housing 120 carries coil 128 whichis connected to a slip ring 127. The slip ring 127 is provided adjacentring 128 mounted in block 129 which is fixed to casing 150 in which thetransmission is mounted. A bearing 130 is provided between the sleeve123 and the casing 129 to provide for relative rotation of the sleeve123 relative to the block 129. Electric current for controlling the coil128 is supplied by wires 134 into ring 128 and then into slip ring 127which rotates relative to ring 128 and slides on the ring 128 so powercan be transmitted from the fixed ring 128 to the slip ring 127 and theninto the coil 128. A brake element 130 is provided within the housing120 and fixed to the control shaft 30. Cavity 132 between the brakeelement 130 and the coil 128 is filled with a non-permanentlymagnetisable material such as ferromagnetic material. When current issupplied to the coil 128 the ferromagnetic material progressivelyprovides an impedance to the brake element 130 to thereby control thespeed of rotation of the control shaft 30 relative to the input cage 42.

Thus, in this embodiment of the invention drive is transmitted from theinput shaft 27 to the cage 42, the planet cluster 60 and then to thesunwheel 70. Because the housing 120 of the magnetic clutch 110 is fixedto the cage 42 the housing 120 is rotated with the cage 42. If nocurrent is supplied to coil 128 the cage 120 is able rotate freelyrelative to the brake element 130 and therefore no control over theoutput 30 is supplied by the magnetic clutch 110. Thus, the output shaft20 is driven with the input cage 42 via the input shaft 27 because ofthe transmission of drive from the cage 42 through the planet cluster 60to the first sunwheel 70 which is fixed onto the output shaft 20.

If the magnetic clutch 110 is controlled so that the coil 128 iseffectively locked onto the brake element 130 so that the brake element130 rotates with the housing 120, the control shaft 30 is thereforerotated at the same speed as the input cage 42 and the drive ratio ofthe transmission is set at 1:1. Once again, if the control shaft rotatesat a lower speed the drive ratio can change from 1:1 down to neutraldepending on the relative speed differential. Neutral is achieved whenthe control shaft 30 is rotating quite slowly just before it stops. Inorder to stop the control shaft 30 so as to provide the reverse gear thesecond magnetic clutch 120 is energised to completely stop the controlshaft 30 from rotating. In the embodiment of FIG. 5 the second magneticclutch 130 is shown mounted directly on the control shaft 30 beside thefirst clutch 110 rather than being connected via the belt 124 shown inFIG. 4. Coil 141 of the second clutch 120 is mounted within the casing150 and a brake element 142 of the second clutch 120 is fixed onto thecontrol shaft 30 in the same manner as the brake element 130. Thus, whenthe coil 141 is fully energised to completely lock the brake element 142to the coil 141 the shaft 30 is prevented from rotating because the coil141 is fixed onto the casing 150. Once the shaft 30 is prevented fromrotating the output shaft 20 is caused to rotate backwards by the drivetransmitted from the cage 42 to the planet cluster 60 to the sunwheel 70and therefore to the output shaft 20 thereby providing reverse gear.Thus, reverse gear is simply provided by controlling the second clutch120 via the control 126 to cause the magnetic clutch 120 to provide fullbraking and therefore full coupling of the coil 141 to the brake element142 so no rotation can occur between the element 142 and the coil 141because the coil 141 is held fixed in the casing 150 the control shaft30 is therefore completely stopped and held stationary. When it is nolonger required to place the transmission into reverse the power to thecoil 141 is stopped thereby releasing the braking effect of the secondclutch 120 so that the control shaft 30 can then rotate under theinfluence of the control signals applied to the first magnetic clutch110.

As in the earlier embodiment, if the control shaft 30 is controlled sothat it rotates faster than the input cage the transmission goes intooverdrive.

Although in the embodiment described above the second magnetic clutch120 is used only for completely stopping the control shaft 30 to providereverse gear, the second magnetic clutch 120 can also be used incombination with the first magnetic clutch 110 so as to provide precisecontrol over the ratio set in the transmission. This can be achieved bycontrolling the magnetic clutches 110 and 120 to provide the brakingpreviously described without fully locking the magnetic clutch 120 tostop the control shaft. The second magnetic clutch 120, apart fromproviding reverse gear, can also thereby provide some additional controlover movement of the control shaft 30 that precise ratios can be set ifdesired.

The ability to use the second magnetic clutch 120 to assist in settingand controlling the drive ratio of the transmission in the embodimentdescribed above is quite important because the effective “dynamic range”of the first magnetic clutch between fully locked on condition and fullyreleased condition is relatively short. Therefore, it can be difficultto precisely set the drive ratio of the transmission or control thedrive ratio of the transmission with only the first magnetic clutchoperating. Using the second magnetic clutch provides a rapid means ofcorrecting any error in the drive ratio which is set by the firstmagnetic clutch by quickly switching the second magnetic clutch on toprovide an impedance or slight braking of the control shaft 30 inresponse to any over correction or adjustment of the control shaft, andtherefore over correction or adjustment of the drive ratio of thetransmission, which is set upon operation of the first magnetic clutch110. Thus, by using the first and second magnetic clutches incombination the drive ratio of the transmission can be more quickly andaccurately adjusted and set in accordance with the driving conditionswhich the transmission is experiencing and the drive ratio which isactually required or set by an operator.

The control of the magnetic clutches is substantially identical to thecontrol of the control motor 28 in the earlier embodiment and generallythe same control circuit to be described with reference to FIGS. 10 and11 can be utilised. The magnetic clutches 110 and 120 are controlled byvarying the duty cycle or pulse width of a signal supplied to theclutches so as to cause the gradual and progressive braking of theclutches to provide the required speed control over the shaft 30. Forexample, if no signal is applied to the coils of these clutches, inother words a signal having 0 duty cycle is applied, then the brakeelements 130 and 142 are able to rotate freely. If a signal having a100% duty cycle is supplied to the coils 128 and 141 the brake elements130 and 142 are caused to lock fixed to the coils so that the brakeelements cannot move relative to the coils and, in the case of theclutch 110 the brake element 130 and therefore the control shaft 30 willrotate with the coil 128 and therefore the cage 120 and input cage 42,and in the case of the clutch 120 the brake element 142 would remainstationary since the coil 141 is fixed stationary. If a signal having aduty cycle somewhere between 0 and 100% is supplied to the coils 128 and141 then a partial braking effect is provided which, in the case of theclutch 120 will cause the brake element 130 to be dragged around withthe coil 128 and housing 120 with a prescribed degree of slippage whichis proportional to the duty cycle of the signals supplied. Thus, byvarying the duty cycle the speed of rotation of the control shaft 30relative to the input cage 42 can be set so as to set the speed of thecontrol shaft 30 to set the drive ratio of the transmission.

As can be seen in FIG. 5 the second clutch 120 is mounted on bearings145 to allow for rotation of the control shaft and the brake element 142relative to the coil 141 and the casing 150 when no power is supplied tothe coil 141.

As in the earlier embodiments the control shaft 30 is mounted onto theoutput shaft 20 by bearings 147. The input shaft 27 is also mounted onthe output shaft 20 via bearings 148 to provide relative rotationbetween the output shaft 20 and the input 27.

In the embodiment of FIG. 5 the output shaft 20 is shown extendingcompletely through the transmission. However, the output shaft need notextend any further than the first sunwheel 70 and the input 27 could bemounted on a lay shaft or otherwise journalled for rotation if desired.The arrangement shown in FIG. 5, as previously mentioned, simplyprovides configuration in which output power can be taken from eitherend of the transmission as is required.

FIG. 6 shows a still further embodiment of the invention. In thisembodiment input rotary power is supplied by input shaft 170 to sunwheel172 of the dual sunwheel system 18. Second sunwheel 174 is connected tooutput shaft 20. Cage 176 supports a plurality of planet systems 60which, in this embodiment comprise a first planet gear 162 which is inmesh with the sunwheel 172 and a second planet gear 178 which is in meshwith the sunwheel 174. The gear 178 is formed separate from the gear 162and meshes with the gear 162. The gears 162 and 178 are supported onseparate shafts journalled in the planet cage 176.

Planet cage 176 carries a control gear 179 which is integral with thecage 176 or fixed onto the cage 176.

In this embodiment of the invention the input rotary power is suppliedfrom a motor (not shown) to the input shaft 172 which rotates thesunwheel 172. Drive is transmitted to the planet gear 162 and then tothe planet gear 178 which in turn, rotates the sunwheel 174. Rotation ofthe sunwheel 174 drives the output 20. In order to change the driveratio of the transmission the cage 174 is caused to advance or regressrelative to the sunwheel 172 by supplying drive to the gear 179.Advancing or regressing the cage 176 will cause the planet cluster 60 toadvance or regress the sunwheel 174 thereby changing the drive ratio ofthe shaft 20 relative to the shaft 170.

The gear 179 is controlled to in turn control the rotation of the cage176 by a control motor 28 which is the same as that previouslydescribed. The control system of this embodiment is shown in dottedlines and can include a lay shaft 191 connected to the motor 128. Thelay shaft 191 carries a transfer gear 191 a which is in mesh with thegear 179 so that by controlling the motor 28 the gear 191 a is rotatedto rotate the gear 179 and the cage 176.

In other arrangements the control may be preformed by a magnetic clutch110 shown in dotted lines in FIG. 6 which is the same as that describedwith reference to FIG. 5. In this embodiment the magnetic clutch isconnected to the input shaft 170 and also to the cage 176 via the stemportion 182 of the cage 176. As in the earlier embodiment, the coil canbe mounted onto the shaft 170 and the brake element onto the stem 182 sothat, depending on the signal supplied to the clutch 110 the stem 182and the cage 176 is caused to rotate at a speed which is eitheridentical to the input shaft speed or a described ratio with respect tothe input shaft speed depending on the signal which is supplied to theclutch 110.

The embodiment of FIG. 6 has particular application to controlling thespeed of machines which include one or more rollers and which arecoupled to the output shaft 20 so as to enable at least one of thoserollers to rotate at a precise drive ratio to other rollers. This, inturn, requires the machine to be able to control the drive ratio of theoutput shaft 20 very precisely so that the drive ratio between variousrollers in the machine can be set. Thus, in this embodiment of theinvention only forward rotation of the output shaft 20 is required and areverse is never needed.

As shown in FIG. 6 the cage 176 is supported on bearings 180 by the stemportion 182. A casing 190 is arranged around the transmission andincludes cover plates 192 and 196 which are either bolted to or fixedintegral to the casing 190 and which mount on bearings 197. As alsoshown the cage 176 is mounted onto the output shaft 20 via bearing 199to provide for relative rotation between the cage 176 and the outputshaft 20.

Although in FIG. 6 the transmission has been described primarily withthe shaft 170 acting as the input and which is driven by motor 110 andratio control being achieved by controlling the cage 176, thistransmission can be considered as a duel input system in which drivethrough both of the input shaft 170 and cage 176 power the transmission.In this case, the speed of the transmission is controlled by driving thecage 176, while the motor 110 which drives the shaft 170 is used as atension sensing device and will modify the ratios produced by thecontrol of the cage 176.

In this embodiment the motor 28 which controls the cage 176 can be asimple three phase motor and the nature of the control can be by way ofthe motor controller of the three phase motor.

The gear box of FIG. 6 is designed to perform very slow changes in ratioand to operate under constant load. The speed of the transmission iscontrolled by the motor 28 and the uncontrolled motor 110 simply sensesthe tension on the output shaft 20 through the process of what is knownas slip in the motor 110.

Although the embodiment of FIG. 6 has been described in terms of theinput power supply being introduced into the shaft 170, which in otherembodiments is described as the control shaft, and control beingperformed by manipulation of the cage 176, the control is neverthelessperformed by relative speed variation between the cage 176 and the shaft170. Thus, for all intents and purposes, this embodiment could still beregarded as the same as the earlier embodiments in which input drive isprovided into the cage 176 and control is provided by rotation of theshaft 170.

FIGS. 7 to 9 show first different embodiments of planet cluster system60 which can be utilised in the preferred embodiments of the invention.FIG. 7 shows a configuration similar to that shown in FIG. 3 except inthis embodiment the first sunwheel is larger than the second sunwheel 80and the first planet gear 62 of the cluster 60 is smaller than thesecond planet gear 64. This form of planet cluster 60 and sunwheelconfiguration can be used in systems;

in which no reverse gear is required. In this system the output ratio isequal to$\frac{1}{\left( {1 - \left( {{A/B} \times {C/D}} \right)} \right.}$with control shaft stationary;

the control gear ratio is$\frac{1}{\left( {1 - \left( {{B/A} \times {D/C}} \right)} \right.}$with stationary (Neutral);

where A, B, C are the number of teeth on the sunwheel 80, second planetgear 64, first planet gear 62 and first planet gear 70 respectively.

FIG. 8 shows a system in which very high or very precise ratios arerequired. In this embodiment the first and second planet gear 62 and 64are separated from one and other and mesh with an idler gear 200. Thedrive ratio can be determined in accordance with the equation referredto above and the idler gear 200 need not be considered.

FIG. 9 shows an arrangement in which the planet gear 64 carries aintegral gear 201 which in turn meshes with the gear 62. The gear 201 issmaller than the gear 64. In this embodiment overdrive gear ratios canbe provided and the control shaft 30 can turn in the same direction asthe input.

The drive ratio is set by the following equation, in which A, B, C and Dhave the same meaning as described above. $\begin{matrix}{{R\quad{output}} = \frac{1}{\left( {1 - \left( {{A/B} \times {C/D}} \right)} \right.}} \\{{R\quad{control}} = \frac{1}{\left( {1 - \left( {{B/A} \times {D/C}} \right)} \right.}}\end{matrix}$when in neutral

FIGS. 10 and 11 show control circuitry for monitoring the speed of theinput cage 42, the output shaft 20, and the control shaft 30. Aspreviously explained the control shaft 30 and the input cage 42 areprovided with a chopper wheel 90 which has a plurality of slots andwhich with the respective cage 42 or control shaft 30.

In order to provide the control, any two of the speed of the input cage42, the output shaft 20 or the control shaft 30 needs to be measured. Ifthe speed of any two of the input cage 42, the output shaft 20 and thecontrol shaft 30 is known, the speed of the remaining one of the inputcage 42, the output shaft 20 and the control shaft 30 can be determined.This is because the speed of all of these components are interrelated bya function which is dependent on the number of teeth on the gears in theplanetary system and on the sunwheels. Thus, for any particular speed oftwo of the input cage 42, the output shaft 20 and the control shaft 30,the speed of the remaining one of the input cage 42, the output shaft 20and the control shaft 30 can be calculated. This relationship can beseen in FIG. 21, which will be described in more detail hereinafter bythe trace T in that figure. As is apparent from the figure, the X axisis the speed of the control shaft 30 and the Y axis is the ratio of theinput speed to the output speed. Thus, by measuring, for example, thespeed of the control shaft, an indirect measure of the speed of theoutput shaft is also provided. Thus, the speed of the control shaft infact provides an indication of the speed of the output shaft. In otherwords, by determining the ratio of the transmission (ie. the ratio ofthe input to the output, which is the Y axis in FIG. 21), and bydetermining where that ratio intersects the trace T, the control shaftspeed can be determined from the X axis. In order to obtain a measure ofthe output speed from the control shaft speed, if the input shaft speedis known, the reverse can happen. This could be done mathematically ifthe mathematical function represented by the trace T is known, or asimple look-up table of input to output ratios with correspondingcontrol shaft speeds could be provided in the processing circuitry sothe processor can simply select the unknown speed from the table if theother two speeds are provided.

In the embodiment of FIG. 10, and also in the embodiment of FIGS. 24 and25, the actual measured speed is the speed of the input 42 and theoutput 20 (and the corresponding input and output in the embodimentdescribed with reference to FIGS. 24 and 25). However, the speed of theinput cage 42 and the control shaft 30 could also be used with thecontrol shaft speed being used as a proportional indication of the speedof the output shaft. Thus, only two of the three parameters referred toabove need be measured, although, if desired, all three of theparameters could be measured and utilised.

FIG. 10 shows how the rotary speed of the input cage 42 or the outputshaft 20 is measured. Each of the chopper wheels 90 is provided with aphoto-interrupter 92 which includes a light emitting diode 301 and alight sensitive transistor 302. The chopper wheel 90 is disposed betweenthe diode 301 and transistor 302 so each time a slot of the chopperwheel 90 interposes between the diode 301 and transistor 302 light isable to be transmitted from the diode to the transistor to cause thetransistor 302 to conduct.

As is shown in FIG. 10 the diode 301 is connected to a 12 volt source ofvoltage via resistor 303 and the transistor 302 is connected to a 9 voltsource of voltage via transistor 304. A buffer 305 is connected betweenthe resistor 304 and the transistor 302 so that the buffer 305 receivesa pulse each time one of the slots in the wheel 90 causes the transistor302 to change state from a conducting condition to a non-conductingcondition. The buffer 305 has an output line 306 which connects to adiode 307. The output line 306 is connected to 9 volt voltage source viaresistor 308 and a second buffer 309 is connected to the diode 307 byline 310. Resistor 311 connects between the 9 volt voltage source andline 310 between the diode 307 and the buffer 309.

The buffer 305 is also connected via resistor 312 to the 9 volt voltagesource and via compacitor 313 to ground to provide power andconventional control to the operation of the buffer 305. The buffer 305acts to condition the pulse received on line 314 into a square wavepulse and diode 307 and resistor 311 convert the square wave outputpulse received on line 306 from the buffer 305 to a series of spikes byremoving the high or positive component of the square wave pulses tothereby leave the low or negative component to producing a series ofspikes of a particular frequency on line 310 which are received by thesecond buffer 309. The buffer 309 is connected to resistor 316 and alsocompacitor 317 which set a time delay in the buffer 309 so each pulseoutput from the buffer 309 is time delayed by a particular amount set bythe value of the resistor 316 and compacitor 317. The output from thebuffer 309 is provided on line 320 via resistor 321 to operationamplifier 322. The operational amplifier 322 receives the pulses fromthe buffer 309 and produces an output voltage which is proportional tothe frequency of the pulses of for example, between 0 and 8.5 volts. Ameter 323 can be connected in parallel with the operational amplifier322 simply for providing an indication of the nature of the signaloutput from the operational amplifier 322.

The circuit showing FIG. 10 is therefore a circuit which convertsfrequency to voltage to thereby obtain a voltage signal which isproportional to the rotary speed of the chopper wheel 90 and thereforethe respective input cage 42 or output shaft 20.

The circuit showing FIG. 10 may include additional compacitors 325 andresistor 326 which act to provide required signal conditioning andfiltering.

Thus, the circuit shown in FIG. 10 produces a DC voltage at output 340between, for example, 0 volts and 8.5 volts, which is proportional tothe speed of rotation of the output shaft 20 or the input cage 42 as thecase may be.

With reference to FIG. 11, the output 340 which relates to the inputcage 42 is supplied on line 340′ in FIG. 11 and the output from thecircuit which is associated with the output shaft 20 appears on line340″ in FIG. 11. Line 340″ is connected directly to a pot 350. The line340′ is connected to an invertor 351 which inverts the voltage signal online 340′ so that, for example, if a 5 volt signal appears on line 340′the output 352 of the invertor 351 is −5 volts, The invertor 351 has aresistor 353 connector to one of its inputs merely to stop offset errorsand assist proper operation of the invertor 351. The invertor 351 mayalso be provided with a trim-pot circuit 353 which can change the natureof the inversion of the invertor 351 should that be desired ornecessary. For example, if something other than the inverted signal isrequired at output 352 then the trim-pot circuit 353 can be adjusted to,for example, in the case of a five volt signal on line 340′ provided a 4volt signal on line 352 should that be required or necessary. This typeof alternation of the signal could be used if it is desired to, forexample, sense the speed of the control shaft, rather than the outputshaft and by appropriate setting of the pot, convert the voltage valueto a voltage representative of the output shaft speed in accordance withthe functional relationship described with reference to FIG. 21 or froman appropriate look-up table.

Alternatively, the trim-pot circuit 353 can be adjusted to ensure thatthe signal on line 352 is of the same magnitude but of oppositeplurality to that on line 340′ should that be necessary.

The trim-pot 350 has a wiper arm 355 which is connected to line 357. Theline 357 connects to ground via a capacitor 358 which removes high speederroneous signals which may be generated from the pot 350.

The pot 350 provides the ratio transmission control function and wouldact as an input in order to change the drive ratio of the transmission.For example, the pot 351 could be under the control of gear shift orother device in order to provide gear changes within a vehicle withinwhich the transmission is installed.

As will be explained in more detail hereinafter by changing the wiper355 the output from the wiper 355 on line 357 will change which willcause a change to the drive ratio of the transmission. If we assume, forexample, that the input cage 42 and the output shaft 20 are rotating atthe same speed then the same voltage signals are applied on lines 340″and 340′. If the wiper 355 is set at its mid point then the signalsapplied to the pot 350 cancel each other out because the signal on line340′ has been inverted by the invertor 351. Thus, if the wiper 355 is atits mid point 0 volts appear at line 357. By changing the position ofthe wiper the drive ratio can be set because of the different voltageratio set by the pot 350. For example, the wiper 355 can be moved by thegear change (not shown) so that in order to produce the 0 volts at thewiper 355 the signal on line 340″ must, for example, be higher than thesignal on line 340′, indicative of the fact that the output shaft istravelling at a different speed to the input thereby producing aparticular ratio which is set by the driver by manipulation of the gearshift.

Line 357 is connected to the non inverting input of a first operationalamplifier 360 and a second operational amplifier 362. The invertinginput of the operational amplifier 360 is connected via line 363 to amotor pre-set pot 364. The inverting input of the amplifier 362 isconnected to a generator pre-set pot 366 via line 367. The lines 363 and367 are connected by line 368 which includes capacitors 370. A saw toothsignal input 371 is connected to a pot 372 which in turn has a wiper 373connected to buffer 374 which has an output 375 which connects betweenthe capacitors 370. A saw tooth signal is supplied to the line 371 froma saw tooth wave generator (not shown) and the pot 372 acts as a loopgain in order to set the frequency or size of the saw tooth wave whichis supplied by the buffer 374 to the output 375. The capacitors 370isolate the DC voltage received on lines 364 and 367 and allow the sawtooth signal to be supplied to the inverting inputs of the operationalamplifiers 360 and 362.

The pots 364 and 366 are set to shift the voltage on the invertinginputs of the operational amplifiers 360 and 362 away from 0 volts bydifferent amounts so that field effect transistors 380 and 382 will beswitched on and off at different times and cannot be switched ontogether as will be explained in more detail hereinafter for the reasonswhich will also be explained in more detail hereinafter.

The offset set by the pot 366 is a slight positive voltage above 0 voltsand the offset which is set by the pot 364 is a slight negative voltageof the same magnitude below 0 volts.

The operational amplifiers 360 and 362 therefore receive on their noninverting inputs the voltage signals supplied by the wiper 355. If weassume that the voltage signal is positive voltage indicating that thecontrol shaft 30 is relating at a higher speed than is required, as setby the gear shift and the position of the wiper 355, a high output willappear on line 385 and 386 from the operational amplifiers 362 and 360.The signal on lines 385 and 386 is inverted by invertors 387 and 388 sothat a low signal is supplied to buffers 390 and 392. The invertors 387and 388 are provided to clean up the edge of the signals received fromthe amplifiers 362 and 360 and the invertors also act to assist inconditioning of the signal because they basically ignore small voltagechanges and only switch large voltage changes. The signal which issupplied to the buffer 390 or 392 from the invertors 387 or 388 appearson output lines 395 from the buffers and is used to control thetransistors 380 and 382 to either place the motor 28 into a drivingcondition where it can drive the control shaft 30 (to speed it up) or ina generator condition in which the motor actually generates power tosupply to a load 410 and impedes the control shaft 30. The actualinversion of the signal from the operational amplifiers 362 and 360 isnot required and if the signal is not inverted (and otherwiseconditioned for supply to the buffers 390 and 392) the high signal fromamplifiers 360 and 362 could simply be input to the inverting inputs ofthe buffers 390 and 392 so that output from the buffers on line 395 and396 is low.

Resistors 398 and capacitors 399 provide signal conditioning and stopstray signals from the power supply from upsetting operation of theoperational amplifiers 360 an 362.

The field effect transistor 380 is a P channel transistor and the fieldeffect transistor 382 is an N channel transistor. Transistor 380 has itsgate connected to the 12 volt voltage supply whereas the transistor 382has its gate connected to ground.

A load 410 is connected between the transistors 380 and 382. Controlmotor 28 for controlling the speed of the control shaft 30 is connectedbetween the 12 volt supply and a point between the load 410 and thetransistor 382.

The transistor 382 forms a motor control transistor for driving themotor and the transistor 380 forms a generating control transistor forallowing the motor 28 to provide generated electric power to the load410.

A meter 422 may be connected in series with the motor for measuring thecurrent through the motor and shunt resistors 423 are connected acrossthe motor 422 to enable the voltage signal to be read from the meter422.

The voltage across the motor 422 is also supplied at point 424 to acurrent shut off circuit 444 at point 445.

When the output from the operational amplifiers 385 is high indicatingthat the output shaft 20 is rotating at higher speed than required andtherefore that the transmission is in a higher gear than required thetransistor 380 is turned on by the low signal on line 395 and thetransistor 382 is turned off by the low signal on line 397. Thus, poweris not supplied to the motor 28 and the spinning of the motor 28 becauseit is connected to the control shaft 30 causes the motor 28 to actuallygenerate electricity which is supplied to the load 410. Since the motoris no longer powered it impedes the control shaft 30 to reduce the speedof the control shaft 30 until the output shaft 20 is at the requiredspeed to produce the 0 volts at the wiper 355.

If the motor 28 is running faster than is required because of the speedof the control shaft 30, which may be the case during regenerativebraking situations or if the vehicle is suddenly under less load, forexample, if it begins to travel downhill, the motor 28 can thereforegenerate power and supply the power to load 410 for either rechargingbatteries or for any other use of electrical power which may be requiredby the vehicle or system in which the transmission is installed.

If the input speed into the transmission is too high so that the signalon line 340′ is of higher magnitude than the signal on line 340″ then anegative voltage will appear at wiper 355 which is supplied to theamplifiers 360 and 362. This will produce a high signal at thetransistors 380 and 382 which will cause the transistor 380 to switchoff and the transistor 382 to switch on. When the transistor 382 isswitched on power is able to flow from the supply voltage source throughthe motor 28 and the transistor 382 to thereby drive the motor 28. Bydriving the motor 28 the motor will speed up the control shaft 30 so asto adjust the drive ratio of the transmission. This form of adjustmentcontinues to happen depending on the position of the wiper 355 andtherefore the gear in which the transmission is set so as to produce a 0voltage at the wiper 355. When 0 volts appears at the wiper 355 thetransistors 380 and 382 are effectively switched off so that the motor28 is not driven, nor does it generate because the rotation speed of thecontrol shaft 30 is correct and the transmission is therefore in thecorrect drive ratio. Thus, the circuit shown in FIG. 11 continuallyattempts to bring the voltage at the wiper 355 to 0 and the rotationalspeed at the control shaft 30 is therefore set depending on the positionof the wiper 355 to set the drive ratio of the transmission.

The manner in which the motor is switched on and switched off will bedescribed in more detail hereinafter.

The diodes 381 prevent any transient during switching on and off of themotor 28 from being supplied to the transistors 380 and 382 and willresult in any such transient voltage merely being conducted to the powersupply to prevent damage to the transistors 380 and 382.

When the voltage of the wiper 355 is 0 or very close to 0 volts then thetransistors 380 and 382 will toggle on and off causing the motor 28 tocontinuously switch between a powered condition when the transistor 382is on and power is supplied through the motor 28, to a generatingcondition when the transistor 380 is on and power is effectively switchoff to the motor 28.

At extreme positive or negative voltages at the wiper 355 the motor 28can either be switched on to drive all the time or switched offcompletely so it is fully generative. When the motor is switched on allthe time the control signal has a duty cycle of 100% and when the motoris switched off all the time the control signal has a duty cycle of 0%.

At voltages in between the extreme voltage and 0 voltage, some degree ofswitching on and off of the motor 28 takes place in accordance with theduty cycle or pulse width of the signals which apply to the transistors380 and 382 as will be explained in more detail hereinafter.

As previously explained, the generator preset pot 366 and the motorpreset pot 364 are set so that the inverting inputs of the operationalamplifiers 362 and 360 are set differently. The result of this is thatthe two transistors 380 and 382 can never be switched on at the sametime and that there is a delay between the time that one of thetransistors is switched off and the other is switched on so they do notconduct at the same time. If the transistors 380 and 382 conduct at thesame time then supply of power completely bypasses the motor 28 and maydamage the transistors 380 and 382 or simply heat up the load 410 andpossibly damage it. The overlap or underlap of the on and off signalssupplied to the transistors 380 and 382 from the buffers 390 and 392 istherefore set by adjusting the pots 366 and 372 to ensure that thevoltage shift on the inverting inputs of the preamplifiers 360 and 362,from 0 volts, is different.

As previously mentioned, over current sensing circuit 444 connects topoint 424 which provides a signal indicative of the current through themotor 28. If the current is too large, which value is set by pot 450, asignal is supplied to transistor 452 which causes the transistor toswitch on thereby supplying a voltage signal to invertor 453. Thissignal is supplied to invertor 453 and then to buffer 392 to switch thebuffer off so that transistor 382 cannot be switched on therebypreventing the flow of current through the motor 28 and preventingdamage to the motor 28 in the case of an over supply

The buffer 392 is also switched off to prevent the motor 28 from beingdriven when it is desired to place the vehicle in reverse gear. When thevehicle is placed in reverse gear (which is done by causing the outputshaft 20 to become stationary thereby requiring-the motor 28 to notdrive the control shaft 30), a signal from a reverse switch associatedwith the gear shift is supplied via resistor 460 to invertor 462. Theinvertor 462 is connected to invertor 453 via diode 465 so that theinvertor 453 supplies the signal to the buffer 392 to switch off thetransistor 382 and maintain the transistor in the switched off conditionuntil the signal supplied through resistor 460 is removed (indicative ofthe vehicle being taken out of reverse gear).

As previously described, the signal supplied to the inverting input ofthe amplifiers 360 and 362 is a saw tooth signal which is superimposedon the DC signal supplied from the pots 364 and 366.

As is shown in FIGS. 12 and 13 the triangular wave is supplied to theoperational amplifier 362 at the inverting input on line 367 and the DCvoltage from the pot 350 is supplied to the non inverting input on line357. The output from the operational amplifier 362 is therefore in theform of a pulse width signal which is defined by the intersection of theDC signal 490 shown in FIG. 13 and which is supplied on line 357 and thetriangular wave 492 which is supplied on line 367. As the signal 490increases or decreases then the effective pulse width defined by theportion of the signal 390 which intersects the triangular wave andlabelled 500 in FIG. 13 will increase or decrease in length therebychanging the effective pulse width of the signal output from theoperational amplifier 362. Thus, the transistors 380 and 382 arecontrolled variable pulse width signals which are set by the triangularwave 492 and the level of the DC voltage on line 357 to provide pulsewidth control of the motor 28 so that the motor 28 is switch on and offin accordance with the pulse width of the signals supplied to thetransistors on lines 395. Therefore, the motor 28 is controlled inaccordance with a variable pulse width signal which is proportional tothe voltage at the wiper 355 of the pot 350.

Because the pots 364 and 366 are set differently, as has been previouslyexplained, the operational amplifiers 362 effectively switch atdifferent points on the triangular wave because of the different 0voltage offset, set by those pots 364 and 366. If an extreme erroroccurs between the required speed of the output shaft 20 and therequired speed of the input cage 42 a larger extreme voltage errorsignal at wiper 355 will be produced. In these situations only the motoroperational amplifier 360 will change at this extreme level therebyswitching motor 28 on to control the speed of the control shaft 30 toadjust the drive ratio of the transmission to that which is required. Ifthe error voltage signal at the wiper 355 is very small indicative ofvery small changes then the transistors 380 and 382 will effectivelyswitch on and off relatively quickly causing the motor to switch on andoff rapidly to maintain the speed of the control shaft 30 so that driveratio of the transmission is held at the required ratio.

Thus, when the vehicle including the transmission according to thepresent invention is initially started the motor 28 rotates the controlshaft 30 slowly so as to maintain the vehicle in neutral. This can bedon by ensuring that the vehicle can only be started with a gear stickin neutral as in the case of a convention automatic transmission so thatas soon as the transmission system is powered the control circuitry ofFIG. 11 appropriately sets the speed of the control shaft 30 to provideneutral gear. However, in general, because the vehicle is stationary andthere is no load on the control shaft 30 the dual sunwheel system 18will tend to merely go into neutral gear by rotating the sunwheel 80 andtherefore the control shaft 30 because the output shaft 20 isstationary. In order to increase the speed of the vehicle the gear shiftis manipulated to cause the wiper 355 to move to change the voltagedivision ratio set in the pot 350. The nature of the change of the wiper355 is to make the voltage signal on the wiper 355 negative. Thisnegative voltage is applied to the operational amplifiers 360 and 362,the invertors 388 and 387 and the buffers 392 and 390 which, in thiscase, results in a low signal being applied to the transistors 380 and382. This switches the transistor 382 on to cause the motor 28 to bedriven so that motor rotates the control shaft 30 to increase the speedof the control shaft 30. As the speed of the control shaft 30 increasesthe transmission is driven down in ratio (or up in gear to a highergear) towards 1:1 ratio so that the speed of the vehicle increases. Thiswill continue to happen until the voltage signal on the lines 340″ and340′ cause a 0 voltage output at the wiper 355. If the gear shiftcontinues to move into a higher gear then the same process occurs tofurther reduce the gear ratio of the transmission or place thetransmission to a higher gear thereby making the vehicle travel faster.Similarly, if it is desired to increase the drive ratio or place atransmission into a lower gear then the wiper 355 is adjusted bymanipulation of the gear stick or automatic transmission so that thedivided voltage at the pot 350 is positive at the wiper 355. This causesthe transistor 380 to be turned on as previously explained and thetransistor 382 to be turned off so that the motor no longer drives thecontrol shaft 30 so that the control shaft 30 will slow thereby placingthe transmission into a lower gear. This will continue to happen againuntil the voltage of the wiper 355 is 0.

FIGS. 14 to 19 show how the pulse width control of the motor 28 takesplace and also how the transistors 380 and 382 are prevented fromturning on at the same time.

FIGS. 14 an 15 are pulsed diagrams showing the signals supplied to thetransistors 380 and 382 respectively.

As can be seen the saw tooth signal 490 has been lifted up above 0 voltsby the offset voltage supplied by the voltage supplied by the pot 366and the saw tooth wave 490 in FIG. 15 has been moved downwardly by thenegative offset voltage set by pot 364. In FIGS. 14 and 15 VO is thevoltage supplied at the wiper 355 and for the sake of comparison inFIGS. 14 and 15 we will assume that voltage is 0 volts. The saw toothsignal 490 shown in FIGS. 14 and 15 has the frequency of say 3.6 KHzsuitable frequency other than that could be used if desired. Since 0volts are produced at the wiper 355 the transmission system is in theright drive ratio and the control shaft 30 is rotating at the rightspeed to maintain that drive ratio. As can be seen from FIGS. 14 and 15,prior to time t1 transistor 380 is on because a low signal is suppliedto that transistor and transistor 382 is off because a low signal isapplied to that transistor. Thus, no power is supplied to the motor 28and it is not driven. Rotation of the motor 28 by virtue of itsconnection with the control shaft 30 causes the motor 28 to generate andsupply electricity to the load 410 via the transistor 380. At time t1the voltage of the saw tooth wave crosses 0 volts and becomes positiveand therefore the high voltage is supplied to the transistor 380 whichcauses the transistor 380 to switch off. At time t1 the transistor 382is also off because the voltage applied to that transistor is still low.At time t2 the saw tooth voltage applied to the comparative 360 switchesfrom negative to positive and shown in FIG. 15 and transistor 382receives a high signal thereby switching the transistor on. It will beapparent from the graphs in FIGS. 14 and 15 that between times t1 and t2both transistors 380 and 382 are switched off and therefore thetransistor 382 cannot be switched on before the transistor 380 is off.The time t2−t1 is the delay between switching off the transistor 380 andswitching on the transistor 382. The transistor 382 remains switched onuntil time t3 while the saw tooth wave voltage is positive and shown inFIG. 15. At time t3 the saw tooth wave voltage 490 in FIG. 15 again goesnegative thereby switching off the transistor 382. It should be notedthat at this time the saw tooth wave voltage 490 in FIG. 14 and which isapplied to the transistor 380 is still positive thereby maintaining thetransistor 380 off. At time t4 the voltage of the saw tooth wave in FIG.490 goes negative thereby switching the transistor 380 on. It should benoted that between the times t3 and t4 both transistors are switched offagain preventing one transistor from being switched on while the otheris already on. The transistor 380 remains for the time period betweentimes t4 and t5. The transistor 382 is switched off for that entire timeperiod. At time t5 the transistor 380 is switched off as the saw toothwave 490 goes positive in FIG. 14. At this time the transistor 382 isstill switched off because of the voltage of the saw tooth wave at thattime is still negative. At time t6 the transistor 382 is switched on.Thus, it would be appreciated that between times t5 and t6 bothtransistors are switched off. The transistor 382 is switched on fromperiod t6 to t7 while the transistor 380 is maintained off for thatentire period. Thus, the delay between switching one transistor on afterthe other transistor goes off is set by the different offset voltageswhich are supplied to the amplifiers 360 and 362 and which is defined bythe time differences t2−t1, t4−t3, t6−t5 etc shown in FIGS. 14 and 15.Thus, one transistor is always required to switch off before the othercan be switched on.

The graphs is FIGS. 14 and 15 show that when the voltage at the wiper355 is 0 volts or very close to 0 volts the transistors 380 and 382toggle on and off with a duty cycle which is set by the time(t3−t2)÷(t6−t3) in the case of the transistor 382 and time(t4−t1)÷(t5−t4) in the case of the transistor 380. The toggling on andoff of the transistors causes the motor 28 to be driven in short -burstsby pules of power supplied while the transistor 382 is switched on withthose pules of power being determined by the duty cycle referred toabove. Thus, the motor is driven slightly to drive the control shaft 30then switch off so that the control shaft is impeded and so on with afrequency of 3.6 KHz and a duty cycle of the on time to the off timewhich is determined as mentioned above and which is dependant on thevoltage VO at the wiper 355. Thus, during this toggling on an togglingoff the control shaft is driven slightly then slowed whilst the motorgenerates through the load 410, then driven to maintain the 0 volts atthe wiper 355 and maintain the control shaft travelling at the requiredspeed to set the drive ratio regardless of the momentum changes withinthe transmission.

FIGS. 16 and 17 show an extreme condition of the voltage at the wiper355. If we assume that the speed of control shaft 30 is extremely highand producing a high positive voltage at the wiper 355 of VO shown inFIGS. 16 and 17 which is greater than the amplitude of the saw toothvoltage 490 then a continuous high voltage is output from the amplifiers360 and 362 which results in a low signal being applied to thetransistors 380 and 382. This switches the transistor 380 permanently onand the transistor 382 permanently off so that the motor is not drivenand is in the generative state where it supplies electricity through theload 410 and transistor 380. This impedes the control shaft 30 to slowthe control shaft the control shaft will be continuously impeded untilthe voltage VO at the wiper 355 reduces so that it again overlaps thesaw wave signal 490 at which stage the toggling effect described abovewill again begin to commence with a duty cycle dependant on the positionof where the voltage VO overlaps the saw tooth wave 490.

At the opposite extreme where the signal on line 340′ is much higherthan a signal on the line 340″ indicating that input is travelling muchfaster than the control shaft (for the required gear ratio) a negativevoltage is produced at the wiper 355 of amplitude greater than the sawtooth wave amplitude as shown by voltage VO′ in FIGS. 16 and 17. Theopposite effect takes place because the low voltage VO will produce ahigh at the transistor 380 therefore turning the transistor 380 off anda low voltage at the transistor 382 thereby turning the transistor 382on. Thus, the motor is powered by electric current supplied from thepower supply through the motor, through the transistor 382 and to theother terminal of the power supply so the motor 28 is driven to speed upthe control shaft 30 to change the drive ratio of the transmission. Asthe voltage VO′ rises from its extreme negative value towards 0 voltsand overlaps the saw tooth signal 490 the toggling effect again beingsto commence with transistors 380 and 382 being switched on and off witha duty cycle which is set by the position at which the voltage VO′overlaps the saw tooth wave signal 490.

FIGS. 18 and 19 show situations where the voltage VO is somewherebetween 0 volts and the extreme conditions shown in FIGS. 16 and 17 andpositive in magnitude. The transistor 382 is continuously off and thetransistor 380 is switched on but with a duty cycle which is very highin terms of percentage of the on time to the off time, for example, 90%or thereabouts as shown in FIG. 18. At the other extreme when thevoltage VO is negative of the same magnitude the opposite will occur andthe transistor 380 will be switched off for most of the time if not allof the time and the motor 28 will be powered periodically with a dutycycle dependant on the time the transistor 382 is switched on comparedto the time when it is switched off. In this case the duty cycle mightalso be 90%.

Thus, it will be apparent that when the voltage is around about 0 at thewiper 355 the transistors 380 and 382 toggle on and off continuously. Ifthe voltages are at an extreme the motor 28 is either held on orcompletely off so as the control shaft 30 is adjusted to the requiredspeed by either being driven by the motor 28 or by being impeded by themotor 28. The most usual situations where the voltage is not extreme butjust above or below 0 volts there will be a switching on and off of themotor 28 with a duty cycle depending on the value of the voltage at thewiper 355 to cause the motor 28 to be switched on and speed up thecontrol shaft or switched off and slow down the control shaft inproportion to the duty cycle of the switching on and switching off ofthe motor 28. The larger the duty cycle of the signal which switches onthe transistor 382 the faster the motor 28 will rotate to bring thespeed of control shaft 30 up to the required operating speed to placethe transmission in the required drive ratio. Conversely, the greaterthe duty cycle of the transistor 380 the more the impeding of thecontrol shaft to slow the control shaft and the more electricity isgenerated by the motor 28 to supply to the load 410.

It will be apparent from the graphs of FIGS. 14 to 19 that whenever thevoltage at the wiper 355 changes state from a negative to a positivevoltage then this change is applied to the transistors 380 and 382.However, the transistor which is switched on will be switched off alwaysbefore the other transistor is switched on thereby ensuring that thetransistors 380 and 382 are not switched on at the same time. Normallywhen the transmission is holding the ratio set by the wiper 355 therewill be slight fluctuations and the voltage at the wiper 355 willprobably go up and down from the 0 voltage state slightly therebycausing the transistors 380 and 382 to be continually switching on andoff to cause the motor 28 to be driven or stopped to ensure that thecontrol shaft catches up or reduces speed to produce the 0 volt outputat the wiper 355.

As previously mentioned, the drive ratio can be set manually beadjusting the wiper 355 of the pot 350 by effectively coupling the wiper355 through a gear shift stick. In other embodiments the adjustmentcould be automatic and the wiper 355 can be adjusted in positiondependant on various parameters which are sensed by computer control ofa vehicle or engine. Such parameters may include the conventionallysensed parameters including vehicle speed, inlet manifold pressure,load, engine speed etc. Information relating to all of the parameterscan be input to a processor which, from a look-up table, can select anappropriate drive ratio for the operating conditions of the engine andin accordance with the selected ratio can adjust the position of thewiper 355 so as to cause the motor 28 to control the shaft 30 to bringthe transmission to that drive ratio.

As previously described, the magnetic powder clutches 110 and 120 can becontrolled by the same circuit as described with reference to FIGS. 11and 14 to 19. FIG. 20 shows an embodiment of the circuit modified tocontrol the clutches 110 and 120. In this embodiment, the clutch 110 iscoupled between the 12 volt power supply and the other side of the load410 that is in parallel with the transistor 380 and the load 410 and thesecond magnetic clutch 120 is connected in parallel with the transistor382 in the load 410 as shown. When the transistor 382 is on the clutch110 is operated in accordance with the duty cycle of the switching on ofthe transistor 382 in the same manner as previously described so thatthe clutch 110 causes drive to be transmitted to the shaft 30 to speedup the shaft 30. When the transistor 380 is switched on power is suppledto the clutch 120 to cause the clutch 120 to stop the control shaft 30if the clutch 120 is fully locked up. If the control shaft 30 is beingadjusted also by the clutch 120 then the clutch 120 can be switched onand off dependant on the duty cycle of switching on and off thetransistor 380 so that the clutch 120 perform correction control of thespeed of the control shaft 30 to set the desired drive ratio.

Other embodiments of the control circuitry may also be used and theseembodiments include merely coupling the transistors 380 and 382respectively and independently t the magnetic clutches 110 and 120. Inthis embodiment the transistors 380 can be of the same type at theinputs to the operational amplifier 362 are simply reversed.

Furthermore, in the magnetic clutch embodiments the circuitry fordetecting the speed of the output shaft and input and supplying thesignal on lines 340′ and 340″ may use a magnetic sensor rather than aphoto-interrupter in order to provide the signal data. The magneticsensor may include a Hall effect type device or other magnetic sensorwhich provides an output pulse every time a magnetic on the rotatingcomponent passes the sensor.

In still further embodiments in which precise control of ratio is notrequired an AC motor can be used as the motor 28 and the AC motorcontrolled by the conventional AC motor controller. This embodiment hasparticular applications to situations where a drive ratio needs to beset and then not further adjusted such as is the case with someindustrial machinery. By simply controlling the electronic controller todrive the AC motor the speed of the control shaft 30 can be set to therequired speed either by visual inspection or speed measurement.

The specific process used in the transmissions previously described, andwhich will be described with reference to FIGS. 22 and 23, is to rapidlydisplace the momentum of the system back and forth, from the outputmeans, ie sunwheel 70, to the control shaft (ie. sunwheel 80) so as tomaintain a predetermined ratio. Change in ratio is achieved by biasing amomentum gate openings to create a new momentum distribution, and thento stabilise it by precisely sensing angular velocity of the input, theoutput and the control shaft and opening and closing the gate inresponse to a feedback system. For precise operation it is important toopen and close the gate rapidly, 3 kHz is an appropriate speed. It isthe nature of these double sunwheel machines, that they will try torespond to external load and speed conditions and alter the transmissionratio. The control process must in general oppose this except where theratio achieved fits in with the designed ratio control program. This isshown in FIG. 21.

The momentum gate and the manner in which it is biased is achieved, inthe preferred embodiments, by controlling the electric motors andmagnetic clutches as previously described in order for them to controlrotation of the control shaft and therefore the control sunwheel (suchas the sunwheel 80) to enable momentum to be displaced back and forthfrom the output to the sunwheel 80 and the control shaft 20 so themomentum is displaced from the output to the control shaft 20 and storedin the clutches or motor, which can be returned to the output via thecontrol shaft 20, the planet system 60 and the output sunwheel 70.

If an uncontrolled transmission of this kind is operating unloaded atposition (r₁,ω₁), as shown in FIG. 21, experiences a load opposing therotation of the output shaft, momentum will be displaced onto thecontrol shaft by causing it to rotate faster. This will result in theratio changing and the transmission operation moving to the right alongthe curve towards the neutral position, shown in FIG. 21, to be locatedat the asymptote of the hyperbola, which function describes therelationship between the transmission ratio and the angular velocity ofthe control shaft. This situation will continue until a new momentumsituation on the control shaft (due to its mass and new angularvelocity), is able to stabilise at some new position (r₂,ω₂) in FIG. 21.Further, loading will of course cause still further movement to theright, until neutral is reached at the asymptote.

If a momentum gate is fitted to the control shaft, the above process canonly occur while the gate is open. If the gate is closed, momentum isprevented from being displaced onto the control shaft to speed it up andthe ratio will remain at the position (r₁,ω₁) if the gate is opened andclosed to a program that will maintain such a state as the output loadvaries.

The above describes a very simple gate system operating on the positivepart or forward part of the ratio function. Such a gate may be referredto as a positive gate created by a mechanical impedance. A gate can alsobe made operable on the negative or reverse part of the ratio function.This is referred to as a negative gate.

A simple positive gate operating on its own is only able to open andclose the gate in one direction, that is to either displace momentumfrom the control shaft onto the output means, or to prevent anydisplacement. A more sophisticated gate combines a positive and negativegate and is able to close the gate completely, or to open it in eitherdirection.

There are at least three mechanism means of achieving the above.1. To alter the angular velocity of the control shaft by slowing it downby a mechanism impedance or some kind of a brake, or speeding it up, sothat ${\phi\omega}_{1}\begin{matrix} < \\ > \end{matrix}{\phi\omega}_{2}$2. To alter the moment of inertia of the control shaft so that$\phi_{1}\omega\begin{matrix} < \\ > \end{matrix}\phi_{2}\omega$3. To alter both the moment of inertia and the angular rotation of thecontrol shaft so that $\phi_{1}\omega_{1}\begin{matrix} < \\ > \end{matrix}\phi_{2}\omega_{2}$

It should be noted that in situation 2 above, to oppose momentumdisplacement onto the control shaft (close the gate) without alteringthe rotation of the control shaft, the device used to alter the momentof inertia must be controlled by some other method.

In order for a gate to open in both directions, it must be able to applytorque directly to the control shaft, or alternatively use some othermethod of directly transferring momentum to the shaft or else alteringthe moment of inertia to increase the angular velocity of the shaft. Oneway of doing this is to use an electric motor which can be switchedrapidly to either drive the control shaft motion or to impede it byacting as a generator.

A second method of creating a gate which will open in both directionscan include a second switchable brake or clutch operating upon thenegative side of the function. Energy must be taken from the input tospeed up the control shaft across the asymptote and cause reverseoperation. A ratio control program will then rapidly switch both thepositive and the negative gate on and off to achieve the same thing asan electric motor described previously.

FIGS. 22 and 23 show a still further embodiment of the invention whichoperates in accordance with the above description and the principlesdescribed with reference to FIG. 21.

The transmission shown in FIGS. 22 and 23 has an output shaft 600 whichcarries an output sunwheel 602. An input flange 604 is mounted about theshaft 600 on bearings 605 and is coupled to planet cage 606. Inputrotary power may be supplied from a motor or other suitable source (notshown) to the flange 604 to rotate the flange 604 and therefore the cage606.

The cage 606 supports a planet system 607 which comprises a transfergear 608 which has a first gear portion 609 which meshes with sunwheel602 and a second portion 610 which meshes with planet gear 611. Theplanet gear 611 mesh with control sunwheel 612 which is provided oncontrol shaft 614.

In the embodiment described, the transfer gear 608 is elongated so thatthe portions 609 and 610 are merely an extension of one another.However, in other embodiments the portion 610 could be provided on areduced diameter portion so as to provide a different ratio to theportion 609.

As previously described, the planet system 607 can take many differentforms, including all of the forms described with reference to FIGS. 7 to9.

The control shaft 614 is mounted in bearings 617 which, together withbearing 619, support the cage 606 for rotation. Thus, rotation of thecage 606 will carry the planet system 607 so that rotation is impartedto the output sunwheel 602 and therefore to the output shaft 600.

The cage 606 has a reduced diameter portion 620 which carries a gear622. The gear 622 meshes with a gear 623 provided on a cone clutch 624.Cone clutches are well known and therefore need not be described indetail herein. Suffice it to say that the cone clutch 624 has a firstportion 625 which has a conical surface 626. The portion 625 carries thegear 623 which meshes with the gear 622 as shown in FIG. 22. The clutchhas a second portion 628 which has a matching conical surface 629 whichcan move in the direction of double-headed arrow A in FIG. 22 so as tocause the clutch to engage or disengage. A screw thread mechanism 630controls the movement of the portion 628 in the direction ofdouble-headed arrow A to cause the clutch to engage or disengage and thescrew mechanism 628 is operated by a lever 631 which is pushed into andout of the plane of the paper in FIG. 22 by a solenoid 632. The solenoid632 is controlled by a control section which will be describedhereinafter.

The portion 628 also carries a gear 633 which meshes with gear 634 fixedonto the control shaft 614.

A magnetic powder clutch 640 (which is the same as the powder clutchedas previously described) is connected to a gear 641 which also mesheswith the gear 634. In this embodiment of the invention, the controlshaft which controls the rotation of the control sunwheel 612 isprovided in two parts rather than as a single shaft. The two partscomprise the shaft 614 and shaft 639 which is in effect a lay shaftprovided through the magnetic powder clutch and which has its rotationcontrolled by the powder clutch 640. Thus, rotation of the lay shaft639, or in other words, the second part of the control shaft, rotatesthe first part of the control shaft 614 on which the control sunwheel612 is mounted by virtue of the engagement of the shafts 614 and 639 bythe gears 634 and 641.

Thus, in order to change the ratio of the transmission, current issupplied to the powder clutch 640 in the manner previously described.This causes the powder clutch to progressively engage in the mannerpreviously described so that the meshing of the gear 641 with the gear634 progressively slows down the speed of the control shaft 614.Referring to FIG. 21 for example, assuming that the speed of the controlshaft was initial SI and the transmission is in a relatively low gear orhigh ratio, slowing down of the control shaft will cause the gear ratioto move down the trace T in FIG. 21 to decrease the ratio or place thetransmission into a higher gear. When the control shaft 614 iscompletely stopped by complete locking of the powder clutch 640, thegear ratio will be in an overdrive ratio on the graph shown in FIG. 21at ratio 0′ which is the lowest ratio the transmission is designed toprovide. It should be noted that because the powder clutch 640 willsimply stop the shaft 614, but will not rotate it backwards, thetransmission will not go into a gear ratio lower than 0′ and representedby the dotted trace T′ in FIG. 21 because this requires a reverserotation of the transmission to move the speed to the left of the origin(or zero speed) of the axis shown in FIG. 21 and marked 0,0. It shouldbe further noted that if it is desired to rotate the shaft 614 backwardsa motor, as described in earlier embodiments, could be used to furtherincrease the overdrive ratio of the transmission.

Thus, by appropriate control of the current supplied to the clutch 614,as is described previously, the drive ratio can be adjusted along thetrace T between a very high gear ratio approaching the asymptote As downto the maximum overdrive ratio 0′ which is established when the controlshaft 614 is completely stopped.

In order to place the transmission into reverse gear, the cone clutch624 is utilised. As is apparent from FIG. 21, when the transmission isin neutral the trace T is approaching the asymptote As or, in otherwords, the transmission is in extremely high ratio in which the input isobviously rotating but the output shaft 600 is stationary. In order toprovide reverse gear which is shown by the trace R in FIG. 21, it isnecessary to increase the speed of the control shaft 614 to a speedgreater than the speed at where the asymptote As crosses the X axis ofthe graph in FIG. 21. This is achieved by supplying power to thesolenoid 632 which activates the lever 631 to thereby rotate the screwmechanism 630 so that the cone clutch 624 engages by forcing the portion628 to the left in FIG. 22, so the surfaces 626 and 629 fully engage tolock the clutch. Since the clutch is coupled to the input via the cage606 (and in particular by the meshing of the gear 622 with the gear 623)the clutch is rotated so that the gear 633 rotates the gear 634 toincrease the speed of the gear 634 and therefore the shaft 614. Thisdrives the speed to the right in FIG. 21 so that the speed crosses theasymptote As and places the transmission into reverse gear as shown bytrace R. As also shown by trace R, as the speed is forced across theasymptote As, the transmission will initially go into a very high ratiowhere the trace R approaches the asymptote but will then smoothly moveto a gear ratio on the trace R which is set by the gear ratio providedbetween the gears 622, 623 and 633 and 634. This effectively locks thecontrol shaft 614 to the input 619 and the gear ratio can be provided tobe a relatively low reverse gear ratio so the vehicle will move inreverse at a speed which is dependent on the input speed provided by theinput cage 606 and the gear ratio between the above-mentioned gears.

As in the earlier embodiments, in order to control the cone clutch 624and the powder clutch 640, the speed of rotation of the output, theinput and the control shaft are sensed. This may be provided by speedsensors 651 on output shaft 600, sensor: 652 on cage 606 and sensor 652on the control shaft 614. By detecting these speeds and processing thespeeds, an appropriate output signal can be supplied to the magneticpowder clutch 640 to progressively lock the clutch 640 to provide thedesired forward gear ratio, or to release the clutch 614 completely andlock the clutch 624 to provide reverse gear.

It should be noted that in other embodiments, different forms of coneclutch 624 can be provided. The above embodiment utilises a cone clutchwhich is mechanically controlled by a screw mechanism 626. However, theclutch could be controlled by hydraulic control systems or magneticcontrol systems as is well known.

The manner in which momentum is displaced back and forth from thecontrol shaft and the output shaft will be explained. In general, inputrotary power is supplied through the flange 604 to the planet cage 606and via the planet gear system 607 to the output sunwheel 602. If a loadis supplied to the output shaft 600, the planet system 607 willimmediately attempt to transfer the momentum into the control sunwheel612. This will try to turn the gear 634 and the therefore the gear 641and the lay shaft 639 on which the gear 641 is mounted, which is withinthe powder clutch 640. Thus, the momentum will now attempt to reside inthe control shaft 614 and the rotary part (ie. the lay shaft 639) of thepowder clutch 640. If the powder clutch 640 is switched completely off,the momentum will therefore be displaced from the output shaft 600 tothe control shaft 614 and the lay shaft 639. However, if the magneticpowder clutch 640 is activated by supply of current, then the shaft 639is stopped from freely rotating and momentum is forced back via themeshing gears 641 and 634, the control shaft 614 and the control gear614 through the planet system 607, and back to the sunwheel 602 andoutput shaft 600. How much the momentum is transferred back willdetermine the drive ratio of the transmission. Thus, by controlling theclutch 640 and the amount of progressive braking provided by the clutch640, the drive ratio of the transmission can be controlled by providingcontrol over the speed of the control shaft 614 and therefore thecontrol sunwheel 612. This process is a rapid performance of adisplacement of momentum back and forth between the output shaft 600 andthe control shaft 614 and powder clutch 640 and the stability of theratio will depend on accurately switching on and off the clutch 640,which effectively opens and closes the momentum gate to control thedisplacement of momentum from the output shaft 600 to the control shaft614 and lay shaft 639.

In a sophisticated application of the transmission of FIGS. 21 and 22,the cone clutch 624 can also be switched on and off so as to displacemomentum from the output shaft 600 to the control shaft 614. This isadvantageous because, in some instances when the transmission is inoverrun (for example when a drive takes his or her foot off theaccelerator), momentum will not want to be displaced from the outputshaft 600 to the powder clutch 640. By switching the cone clutch 624 on,the momentum is forced to be displaced from the output shaft 600 to thecontrol shaft 614. The second advantage is that this process would makethe displacement of the momentum occur much faster and stabilise theratios much more quickly.

In still further applications, the control shaft 614 may include asection 660 shown in dotted lines, which carries a variable centroidsystem 662, for example the moving mass system, similar to thatdisclosed in our co-pending International Application No.PCT/AU00/00603, the contents of which are incorporated into thisspecification by this reference. The system 662 will assist the clutch640 to manage the momentum displacement process without large use ofenergy by the magnetic clutch 640.

FIGS. 24 to 32 show a further embodiment of a controller which can beused in the preferred embodiments of the invention. The controller ofthese Figures has particular application to the embodiment of FIGS. 22and 23. However, this controller could also be used with the earlierembodiments and the controller described with reference to FIGS. 10 to20 could also be used with the embodiment of FIGS. 22 and 23.

With reference to FIG. 24, the controller has a pair of field effecttransistors 700 and 701 which are connected in parallel with oneanother. Power is supplied to the field effect transistors from abattery 703. A diode 704 is provided to protect the circuitry should abattery of a higher voltage than required be used or the batteryconnected in reverse polarity. A fuse 705 is connected between the diode704 and the battery so that should the voltage supplied by the batterybe too high or the battery connected in reverse polarity, the fuse 705will burn out to thereby shut off power supplied to the circuitry shownin FIG. 24.

Capacitor 706 smooths the voltage supply to the transistors 700 and 701.The transistors 700 and 701 have an output 707 which provides a lockingsignal to solenoid 632 described with reference to FIG. 22 and whichcontrols the cone clutch 624. The transistors 700 and 701 are alsoconnected to a diode 708 and a capacitor 709 is connected in parallelwith the transistors 700 and 701. The diode 708 and the diode 708aensure that the voltage at the output 707 cannot go significantly higherthan the voltage V+ supplied by the battery 703 or below the voltage V−.Typically, the battery 703 is a 12V battery and the voltage V+ is 12Vand V− is 0 volts.

The transistors 700 and 701 receive an input on line 710 from a port 751of a microprocessor 750 shown in FIG. 25 and which will be described inmore detail hereinafter. Thus, in other words, the port 751 of theprocessor 750 is connected to line 710 shown in FIG. 24. As also shownin FIG. 24, the line 710 connects via line 711 to the transistor 701 sothat both of the transistors 700 and 701 are switched on by the signalon line 710.

When the signal is received from the microprocessor 750 on line 751, thetransistors 700 and 701 are therefore switched on to supply a voltage atoutput 707 which activates the solenoid 632 (FIG. 22) so as to lock thecone clutch 624 so that a control shaft 614 is connected to input cage606 to thereby place the transmission of FIG. 22 into reverse gear inthe manner previously described.

The circuit in FIG. 24 also includes a pair of high side driver circuits720 (only one shown). The pair of high side driver-circuits 720 areidentical and therefore only one is shown in FIG. 24. The other driveroperates in the same manner, as will be apparent from the followingdescription. The voltage applied to circuit 720 is stabilised bycapacitor 709.

The driver 720 receives control signals from the microprocessor 750 sothat outputs are supplied on lines 721 and 722 to control field effecttransistors 723 and 724. The other driver (not shown) provides outputsignals in the same fashion to control another pair of field effecttransistors which are identical to those shown in FIG. 24 (and indicatedby reference numeral 723′ and 724′ in FIG. 31).

Turning now to FIG. 25, processor 750 receives signals on line 753 fromsensor 652 shown in FIG. 22, indicative of the speed of rotation of theinput. The line 754 receives signals from the sensor 651 indicative ofthe speed of the output shaft 600. A third input on line 756 may also beprovided which provides a signal indicative of the speed of the controlshaft 614 if desired, and which would come from the sensor 652 shown inFIG. 22.

The processor 750 also receives a signal on line 757 from a reverseswitch circuit 758 which is closed when a driver wishes to place thetransmission into reverse. This happens automatically by actuation of avehicle reverse gear switch indicative of the fact that reverse gear isrequired. The reverse switch circuit 758 includes a diode 759 and thecapacitor 758 which stop interference from spurious signals so that afalse signal will not be provided on line 757. Thus, when the driverplaces the vehicle into reverse, the reverse switch circuit 758 isclosed and a reverse signal provided on line 757 to the processor 750.The processor then determines from other inputs which are received intothe processor 750, whether it is appropriate to place the vehicle intoreverse gear. These other signals will include speed of the vehicle atthe output shaft, etc. so that if the processor 750 determines that thevehicle should not be placed into reverse gear, such as if the vehicleis travelling at high speed in forward direction, then the processorwill not output the locking signal on line 751. However, if theprocessor 750 determines that reverse gear is appropriate, then aswitching signal is applied on line 751 to the line 710 to switch on thetransistors 700 and 701 as previously describes, so that the lockingsignal is provided from output 707 to the solenoid 632 to place thetransmission into reverse gear.

If reverse gear has been selected either erroneously or inappropriatelyand the processor 750 decides that a signal will not be output on line751, the processor 750 can output a signal on line 765 to transistor 766to switch the transistor on so that current flows through coil 767 toactivate a light or alarm shown by reference 768 to indicate erroneousselection of reverse gear. The alarm 768 can also be used to indicateother alarm conditions if required.

The processor 750 also receives an input from pot 760 via line 761 whichis indicative of throttle position of the vehicle. The processor 750 mayalso receive an input indicative of front wheel speed on line 762 andvacuum condition of the engine on line 763.

The processor 750 may also receive signals from an input circuit 770which can be used to change parameters within the processor 750 toeffectively reprogram the processor 750 to operate in accordance withmodified protocols or algorithms as is required. This circuitry can beused in initial set-up or alternatively for servicing or otherrequirements by authorised personnel. This circuitry has no bearing onthe actual function of the device and therefore will not be described inany further detail.

The processor 750 outputs signals on lines 780, 781, 782 and 783. Theline 780 connects with line 730 of driver 720 and the line 781 connectswith line 731 of the driver 720.

The lines 782 and 783 connect to the other driver which is not shown onlines corresponding to lines 731 and 730.

The output lines 721 and 722 of the driver 720 are connected to thefield effect transistors 723 and 724 as previously described so as toswitch on and off the transistors 723 and 724 dependent on whether thesignal on lines 721 or 722 is high or low. When the transistor 723 isswitched on, the transistor can conduct to provide a voltage at output740. When transistor 724 is switched on, the voltage at line 754 iseffectively connected to ground and is therefore zero volts.

Diodes 741 and capacitors 742 protect the transistors 723 and 724 andprevent the voltage across the transistors from increasing above orbelow a predetermined voltage to prevent damage to the transistors 723and 724.

Capacitors 743 and 744 stabilise the voltage supplied to the transistors723 and 724.

Voltage V+is also connected to line 745 via diode 746. The line 745includes capacitor 747 and is connected to output 740 via line 748 whichconnects to the driver 720. The reason for this is to ensure that thevoltage available on line 721 will be above the voltage at output 740 toensure that the transistor 723 is maintained switched on because inorder to hold the transistor 723 on, the voltage on line 721 must beabove the voltage at output 740. Thus, as soon as the transistorswitches on, the capacitor 747 is able to charge up and its dischargewill enable voltage to be supplied to the driver 720 together with thevoltage V+ from the battery for output on line 721 to maintain thetransistor 723 switched on by supplying a voltage on line 721 which isabove the voltage at output 740.

The output 740 and the corresponding output from the other driver 720which is not shown are connected across the powder clutch 640 shown inFIG. 22. FIG. 31 is a simplified diagram illustrating this connection.

The switches shown in this diagram represent the transistors 723 and724. The switches 723′ and 724′ are the field effect transistorsassociated with the driver which is not shown in FIG. 24.

Thus, it can be seen that by closing the switch 723 and the switch 724′,current is supplied through the powder clutch 640. Similarly, by closingthe switches 723′ and 724, reverse polarity power can also be suppliedthrough the powder clutch 640.

FIGS. 26 to 31 show wave forms which are output on the lines 721 and 722to control the transistors 723 and 724 (and also the transistors 723′and 724′). These wave forms are selected by the processor 750 based onthe inputs receives on the lines 753 and 754 which are indicative of thespeed of the input and output (or control shaft) in the transmission,the throttle position 760 and other engine operating data to thereby setthe drive ratio of the transmission. The processor, from those inputs,produces outputs on lines 780 to 783 which are provided to the driver720 (and the driver which is not shown) to cause those drivers to outputsignal on their respective lines 721 and 722 to switch on thetransistors 723 and 724 for the required time period to produce therequired pulses.

FIG. 26 shows a wave form which will cause the powder clutch 640 to lockso that the lay shaft 639 is held stationary and fixed to the casing 640a to thereby stop the control shaft 614 and place the control shaft 614into a stationary condition. This occurs by outputting DC pulses of aparticular duty cycle (which may, for example, be 25% on) to switchtransistors 723 and 724′ on to activate the clutch 640 into the lockedposition.

In order to control the clutch 640 so that some movement of the layshaft 639 is allowed to thereby control the rotation of the shaft 640,the transistors 723, 724, 723′ and 724′ are controlled by an ACfrequency control rather than simply by changing the duty cycle of thepulses as in the control system of the earlier embodiment. In order toproduce the frequency control, the switching of the transistors firstgoes through a DC to AC transition which is best illustrated in FIGS. 27to 30.

This occurs by controlling the transistors so that pulse P1 iseffectively shortened in time duration and a negative pulse P2 of a veryshort duration is produced (FIG. 27). It should be noted that the pulsesare separated in time, in other words, there is a time delay between thepulse P1 and P2. This is achieved by switching on the transistors 723and 724′ to produce the pulse P3 and then switching off thosetransistors. After a time delay, the same transistors are switched onfor a shorter duration to produce the shorter time duration pulse P1.Those transistors are then switched off and, after a delay, thetransistors 723′ and 724 are switched on for a short time period tocreate the negative pulse P2.

As shown in FIG. 28, the time of switching on the transistor 723 and724′ increases so that the pulse P2 increases in duration. It should benoted that the pulse width of the pulses P1 and P3 also change.

As shown by FIG. 29, the pulse width of the pulse P3 and P1 furtherchange as the pulse width of the pulse P2 increases and this continuesto occur until the pulse P1 is effectively zero, thereby just leavingthe pulses P3 and P2 as is shown in FIG. 30. This effectively providesan AC signal with the pulses P2 and P3 being the same duration.

Although the conversion from AC to DC has been shown in only four stepsin FIGS. 27 to 30, obviously additional steps will be used. As isapparent from the drawings, as the pulse P1 decreases in duration, thepulse P3 increases in duration as does the pulse P2 until the situationin FIG. 30 is produced where the signals are of the same duration.

Once the DC to AC conversion has taken place, the control over theclutch 640 now occurs by frequency control by varying the time betweentime T1 and time T2 in FIG. 30, whilst maintaining the pulse width ofthe pulses P2 and P3 and the delay times ΔT₁ and AT₂ in the same ratioas shown in FIG. 30. Thus, each of these durations, including thedurations of the pulses P2 and P3, will decrease so the time from T1 toT3, which is the time of the leading edge of the next pulse P3 in thecycle, decreases. In FIG. 30 the effective wavelength is 48milliseconds. As that time period decreases, the frequency increases tothereby control the powder clutch 640 to alter the amount of rotation ofthe lay shaft 639, which the powder clutch 640 allows, to in turncontrol the speed of the control shaft 614. This form of frequencycontrol can be used to allow the powder clutch 640 to control the speedof the control shaft 614 up to a certain speed.

In order to further speed up the control shaft, the duty cycle of thepulses P3 and P2 is altered so as to change the on time and off time ofthose pulses whilst maintaining the frequency constant to provide ACpulse to control the clutch 640 to provide complete opening of theclutch 640 and therefore freeing the control shaft 614 completely forrotation without any impedance up to speed S1 in FIG. 23.

For convenient data processing within the processor 250, the nature ofthe signals which are output to the driver 720 on the lines 780 to 783to in turn set the time period for which the transistors 723 and 724,etc. are switched on, is divided into intervals of 0 to 255, whichconveniently corresponds to 8 bits of data. By considering theinformation which is received from the speed sensors 651 and 652, thepot 760, vacuum signal on line 763 and possible front wheel speed 762,the processor 750 can determine from those numbers the appropriateoutput to supply to the drivers on the lines 780 to 783 to control thetransistors 723, 724, 723′ and 724′ to in turn control the clutch 640 inthe appropriate manner. For example, and with reference to FIG. 32,number 255 produces the DC pulses which completely lock the clutch 640and stop the control shaft 614. Numbers 254 down to 223 can produce theDC to AC conversion in 32 steps by gradually decreases the pulse widthP1, increasing the pulse width P3 and producing the increasing pulsewidth P2 so as to eventually produce the AC signal shown in FIG. 30.Numbers 223 down to number 31 can produce the frequency control bychanging the time period T3−T1 to thereby produce the changing frequencyso as to perform the control over the clutch 640 which will change thedegree of allowed rotation of the shaft 614 up to the certain speed ofthe control shaft 614. As is shown by the torque curve N in FIG. 32, thechange in pulse width of the signal with constant frequency can occurfrom numbers 31 down to 0 to bring the speed of the control shaft to aspeed S1. The pulse width AC control is desired because to bring thespeed to the speed S1, the powder clutch can no longer follow the torquecurve which would produce simply by frequency control.

FIG. 33 shows a modification to the embodiment of FIGS. 22 and 23. InFIG. 22 the outer housing 640 a of the powder clutch 640 is fixed to thecasing of the transmission and held stationary. In the modifiedembodiment of FIG. 33, the casing 640 a is coupled to the input, as willbe explained below, so that the casing 640 a can rotate. This assiststhe powder clutch 640, maintaining the required control over the controlshaft 614 so that it is not necessary for the powder clutch 640 to workas hard as in the embodiment of FIG. 22. This embodiment of theinvention allows the powder clutch to operate in the region of the graphin FIG. 21 between the speeds S1 shown in FIG. 21 and S2 which is thespeed of the control shaft which will produce the 1 to 1 ratio. Sincethe powder clutch is operating only in this part of the curve of FIG.21, it is more easy to control the powder clutch so that the powderclutch operates satisfactorily to maintain the control of the speed ofthe control shaft 614 to produce the drive ratios between the speeds S1and S2 in FIG. 21. Again, in this embodiment, when it is desired toplace the transmission into reverse gear, the cone clutch previouslydescribed locks the input to the control shaft to increase the speed ofthe control shaft above the speed S1 in FIG. 21 to place thetransmission into reverse gear.

It should be noted that only the modified part of FIG. 22 is shown inFIG. 33 and like reference numerals indicate like parts to thosepreviously described.

In FIG. 33 the lay shaft 639, control shaft 614 and a shaft 901connected to the cone clutch 624 are journaled in casing 900 of thetransmission. The planet cage 600 is shown schematically and carriesring gear 902 which has internal teeth which mesh with pinion 903supported on shaft 904. The other end of the shaft 904 carries a pinion905 which meshes with internal teeth on a ring gear 907 which isjournaled on the end of the control shaft 614.

The control shaft 614 carries gear 634 which meshes with gear 633connected to the cone clutch 624 and the gear 641 on the lay shaft 639as previously described.

The ring gear 907 also has external teeth which mesh with the gear 623of the cone clutch 624 and a gear 907 provided on sleeve 908 whichconnects to outer casing 640 a of the powder clutch 640.

Thus, when the input cage 606 rotates, the pinion 903 is rotated to, inturn, rotate pinion 905 which rotates gear 907. Rotation of gear 907 isimparted to gear 909 which rotates the outer casing 640 a of the powderclutch. In other words, the outer casing 640 a of the powder clutch iscoupled to the cage 606.

Depending on the control signals which are applied to the powder clutch640, this attempts to slow down the speed of the control shaft 614towards the speed of the planet cage 606. Thus, when the powder clutchis fully locked so that the shaft 639 is effectively fixed to the outercasing 640 a, the cage 606 is coupled to the control shaft 614 and thecontrol shaft 614 will rotate at a speed relative to the input cage 606dependent on the gear ratio between the gears 902, 903, 905, 907, 907,909 and 641 and 634. These gear ratios can be chosen to set the lowestgear ratio or highest speed of the transmission and may for example be 1to 1 as described above, or could move the transmission into overdriveif the gear ratio between these gears is such that it results in thecontrol shaft 614 rotating at a speed below the speed S2 shown in FIG.21.

When it is desired to place the vehicle into reverse gear, the powderclutch 640 is completely released which allows the control shaft 614 tospeed up as shown by trace T towards neutral. In other words, the gearratio increases and the transmission goes into low gear approachingneutral. In order to place the transmission into reverse gear, thecontrol shaft 614 needs to be increased in speed beyond the speed S1 aspreviously disclosed, and this is done in the same way as previouslydescribed by activating the cone clutch 624 so that the gear 623 islocked onto the shaft 901 by the cone clutch 624 so that drive istransmitted from the cage 606 via the gear 907 to the gear 623, to theshaft 901 and then to the gear 633 and the gear 634. The drive ratiobetween these gears is such that the speed of the control shaft 614 willincrease in speed, thereby moving the velocity of the control shaft tothe right in FIG. 21 and thereby placing the transmission into reversegear in the same manner as previously described.

It will be noted that since the outer casing 640 a of the powder clutch640 is able to rotate in this embodiment, powder is supplied to theclutch 640 via a slip ring which is the same as the slip ring 127, 128described with reference to FIG. 5.

FIG. 34 shows a still further modification in which the variablecentroid system 662 described with reference to FIG. 23 is provided onthe lay shaft 639. This system operates as disclosed in theaforementioned International application and functions to take furtherload from the powder clutch 640 to further facilitate the control thepowder clutch 640 has over the control shaft 614. As the lay shaftincreases in speed, the moveable masses 920 (only one shown) moveradially outwardly against the bias of springs 921 so as to slow downthe rotation of the shaft 639 to maintain the control over the controlshaft 614. Thus, the combined operation of the powder clutch 640 and thesystem 622 has the effect of slowing down the control shaft 614 tochange the drive ratio from neutral towards 1 to 1 and overdrive ratioas previously described. In this embodiment, not all of the work tocontrol the control shaft 614 to change the drive ratio from neutraltowards 1 to 1 and overdrive therefore needs to be performed by thepowder clutch 640 and the system 622 supplements the operation of thepowder clutch 640.

FIGS. 35 and 36 show a still further embodiment in which the controlover the control shaft 614 is performed by a toroidal pitch transfergear system 950. This gear system is described more fully in ourco-pending Australian Provisional Patent Application No. PR3303 thecontents of which are incorporated into this specification by thisreference. Thus, in this embodiment, the cone clutch and powder clutchare completely removed and the pitch system 950 is controlled by one ormore servo-motors 998 which, in turn, are controlled by control signalsreceived by a controller 999 indicative of the speed of any two of theinput, the output or the control shaft in the same manner as previouslydescribed.

In this embodiment, the sleeve 908 connects to a first toroidal trackvariator 960. The variator 960 rotates with the gear 909 and sleeve 908and carries a toroidal track 961 having gear teeth which change in pitchfrom an inner diameter portion 962 to an outer diameter portion 963. Asecond pitch variator 965 is fixed onto the lay shaft 639 and alsoincludes a toroidal track 966 which forms a track pair with the track961. The track 966 also has toroidal teeth which change in pitch frominner diameter 967 to outer diameter 968 as is described in more detailin the aforesaid provisional application.

A pair of pitch transfer wheels 980 and 981 are mounted between thetracks 961 and 966 and are arranged on rotatable shafts 985. Each of thepitch transfer wheels 980 and 981 comprises two pitch gears having adifferent number of teeth so that the teeth are slightly out of phasewith one another. The two gears are able to move relative to one anotherso as to transfer drive from the variator 960 to the variator 965, as isclearly described in the aforesaid Australian provisional patentapplication. As clearly shown in FIG. 36, the pitch transfer wheels 980and 981 are arranged in cut-outs or slots 987 in the shafts 985 and arejournaled on pivot pins 989 so that the pitch transfer wheels 981 canrotate on the pins 989 to transmit drive from the variator 960 to thevariator 965.

As is best shown in FIG. 36, the shafts 985 (only one shown) aresupported between plates 986 which are shown in FIG. 36. At one end theshafts have lugs 991 which are provided with elongated slots 992. Theslots 992 each receive a pin 993 located on block 994 which is connectedto a screw threaded shaft 995. The screw threaded shaft passes through ascrew threaded nut 996 and is rotated by the servo-motor(s) 998 so thatthe shaft 994 is driven back and forward in the direction of arrow Xrotate the shafts 985, which in turn rotates the pitch transfer gear 981in the directions of double-headed arrow M in FIG. 35. This changes thedrive ratio between the variator 960 and the variator 965 depending onthe rotated position of the shafts 985 and therefore the location of thepitch transfer gears 981 with respect to the toroidal tracks 961 and966. Thus, the drive transmitted from the. cage 606 via the gear 902,pinion 905, gear 907, gear 909, sleeve 908 and then from the variator960 to the variator 985 is altered dependent on the orientation of thepitch transfer gears 981. Thus, the drive transmitted to the shaft 614is altered in accordance with the orientation of those pitch transfergears to thereby control the rotary speed of the shaft 614 to in turncontrol the drive ratio of the transmission.

If the drive ratio between the variators 960 and 965 is high, the shaft614 is therefore slowed down by the drive ratio to thereby place thetransmission into a higher gear, or in other words speed up thetransmission. If the drive ratio between the variator 960 and 965 isdecreased, the control shaft 614 is able to increase in speed therebybringing the transmission down towards neutral. If it is desired toplace the transmission into reverse gear, the drive ratio between thevariator 960 and 965 can be designed so that the speed of the shaft 614can be further increased, thereby placing the drive ratio into reverseas previously described.

Since modifications within the spirit and scope of the invention mayreadily be effected by persons skilled within the art, it is to beunderstood that this invention is not limited to the particularembodiment described by way of example hereinabove.

1. A transmission system including: a dual sunwheel system having afirst sunwheel and a second sunwheel, the first sunwheel providingoutput rotary power when the transmission system is operating; a planetsystem including a first planet gear and a second planet gear coupled tothe first planet gear, the first planet gear meshing with the first sungear and the second planet gear meshing with the second sun gear; a cagefor carrying the planet system; input means for receiving input powerfrom an input power source and supplying the input power to the dualsunwheel system to cause the dual sunwheel system to supply rotary powerat the first sunwheel; control means for controlling the dual sunwheelsystem so as to set the drive ratio of the transmission by causing thefirst sunwheel to advance or regress relative to the input means bydisplacing momentum back and forth between the first sunwheel whichprovides the output rotary power and the control means; and wherein theinput means comprises the planet cage of the dual sunwheel system andthe control means includes a control shaft coupled to the secondsunwheel for rotating the second sunwheel to cause the first sunwheel toadvance or regress relative to the cage to provide for substantiallycontinuous drive ratio change of the output relative to the cage betweenminimum and maximum drive ratios.
 2. The transmission system of claim 1wherein the cage of the sunwheel system is coupled to an epicyclicplanet system, the epicyclic planet system having a first input forinput of power and a second input for input of power, the epicyclicplanet system being connected to the cage of the dual sunwheel system tothereby rotate the cage to provide the input rotatory power into thedual sunwheel system.
 3. The transmission system of claim 2 wherein theepicyclic planet system includes an epicyclic sunwheel, an orbit gearand at least one said epicyclic planet gear, the said epicyclic planetgear being carried by the cage of the dual sunwheel system, a firstinput shaft connected to the epicyclic sunwheel and a second input shaftconnected to the orbit gear so that when either or both of the first orsecond input shafts is rotated the epicyclic planet gear orbits aboutthe epicyclic sunwheel to thereby rotate the cage of the dual sunwheelsystem and provide input rotary power into the dual sunwheel system. 4.A transmission system including: an epicyclic planet system having anorbit gear, a sunwheel and at least one planet gear between the sunwheeland the orbit gear, the orbit gear receiving input rotary power from afirst power source and the sunwheel receiving input rotary power from asecond power source; a dual sunwheel system having a first sunwheel anda second sunwheel, the first sunwheel being coupled to an output shaft;the dual sunwheel system further having a planet system including afirst planet gear in mesh with the first sunwheel and the second planetgear in mesh with the second sunwheel, the first and second planet gearsbeing coupled together, the planet system being supported in a cage, thecage also carrying the at least one planet gear of the epicyclic planetsystem so that when input rotary power is input from the first or secondsource to the orbit gear or the sunwheel of the epicyclic planet systemthe planet gear of the epicyclic system orbits about the sunwheel of theepicyclic planet system to rotate the cage and thereby supply rotarypower to the planet system and to the first sunwheel to drive theoutput; and a control means coupled to the second sunwheel forcontrolling the rotary speed of the second sunwheel which in turnrotates the planet system via the second planet gear to cause the firstsunwheel to advance or regress relative to the cage to thereby changethe drive ratio of the transmission.
 5. The transmission system of claim4 wherein the control means includes: a control circuit having at leasta first sensor and a second sensor for providing respective signalsindicative of the rotary speed of any two of the cage, the secondsunwheel and the output, and processing circuitry for receiving thesignals and for producing a control signal; and a control mechanism fordriving or impeding rotary motion of the second sunwheel dependent onthe control signal.
 6. The transmission system of claim 5 wherein thefirst and second sensors sense the speed of the cage and the outputrespectively.
 7. The transmission system of claim 6 wherein the sensorsdetect the speed of the cage and the second sunwheel, and the speed ofthe second sunwheel is used as an indicative speed of the output.
 8. Thetransmission system of claim 4 wherein the control mechanism comprisesone or more of an electric motor, a magnetic powder brake or clutch, anda mechanical or hydraulic variable drive.
 9. The transmission system ofclaim 5 wherein the processing circuitry includes: means for setting apredetermined ratio between the first and second signals and forproducing an initial control signal indicative of a variation from theset ratio; means for producing the control signal in the form of avariable pulse signal having a duty cycle indicative of the magnitude ofthe initial control signal; and switch means for receiving the variablepulse signal, the switch means being coupled in a power supply to thecontrol mechanism so that the control mechanism is powered by switchingthe switching means on by the variable pulse signal so that the controlmeans is powered on in pulse fashion with a duty cycle dependant on theduty cycle of the control signal so the control shaft is driven toincrease rotary speed when the control mechanism is powered and impedesrotation on the control shaft when the control mechanism is not poweredis set in accordance with the duty cycle of the control signal.
 10. Thetransmission system of claim 9 wherein the switching means comprises atleast one transistor which is provided in series with the controlmechanism so that when the transistor is switched on power is able toflow through the control mechanism to activate the control mechanism toincrease the rotational speed of the second sunwheel.
 11. Thetransmission system of claim 10 wherein the control mechanism is amotor, and a second transistor is arranged in parallel with the motor sothat when the first transistor is switched off, the second transistor isswitched on and current is able to flow through the second transistorand to a load so that in environments in which the motor is running at aspeed higher than the input power to the motor the motor can generateelectricity and supply that electricity to the load and impede therotation of the control shaft.
 12. The transmission system of claim 11wherein the load comprises a battery for supplying power to an electricpropulsion motor in a hybrid power supply system so that the motor canrecharge the batteries depending upon the operating conditions of themotor.
 13. The transmission system of claim 10 wherein the controlcircuity includes current sensing means for sensing current supply tothe motor and, in the event of over supply of current, switching off theswitching means so that current cannot flow through the motor and themotor is de-energised.
 14. The transmission system of claim 5 whereinthe control circuitry also includes a reverse gear signal indicatingmeans for providing a reverse signal when the transmission system isplaced in reverse for preventing the switching means from switching onso as to maintain the motor in a switched off condition when the vehicleis in reverse gear.
 15. A transmission system including: a dual sunwheelsystem including a first sunwheel provided on an output shaft forsupplying output rotary power, and a second sunwheel; a control shaftcoupled to the second sunwheel; a planet system having at least a firstplanet gear in mesh with the first sunwheel and a second planet gear inmesh with the second sunwheel; a cage for carrying the planet system;input rotary power supply means for supplying input rotary power to thecage; and control means for controlling the speed of rotation of thecontrol shaft to control the speed of rotation of the second sunwheel toset the drive ratio of the transmission.
 16. The transmission system ofclaim 15 wherein the control means comprises a control motor forcontrolling rotation of the control shaft.
 17. The transmission systemof claim 15 wherein the control means comprises a first magnetic powderclutch having a first component including a coil and a second componentincluding a brake element, the first component being coupled to eitherthe cage or the control shaft, and the second component being coupled tothe other of the cage or the control shaft so the component which iscoupled to the cage rotates with the cage upon supply of input rotarypower to the transmission system, and control power supply means forsupplying a control signal to enable energisation of the coil to causethe magnetic clutch to activate so as to progressively lock thecomponent having the coil to the component having the brake element sothat rotation is transmitted from the component coupled to the cage tothe component coupled to the control shaft to thereby make the controlshaft rotate in accordance with the control signal supplied to the coil.18. The transmission system of claim 17 wherein a second magnetic powderclutch of the same structure as the first magnetic clutch is alsoprovided, the second magnetic clutch having its first component fixedstationary and its second component coupled to the control shaft so thatwhen a control signal is supplied to energise the second magnetic clutchthe second magnetic clutch can completely lock-up to prevent rotation ofthe control shaft to thereby cause the control shaft to remainstationary and thereby place the transmission system into reverse gear.19. The transmission system of claim 17 wherein the first magneticclutch has the first component including the coil coupled to the cagefor rotation with the cage, the first component including a slip ringfor engaging a ring fixed stationary in the transmission system socontrol signals can be supplied via the fixed ring to the slip ring andto the coil in the first component.
 20. The transmission system of claim15 wherein the planet system comprises the first planet gear and thesecond planet gear fixed integral with the first planet gear, theintegral first and second planet gears being mounted on a shaft fixed tothe cage.
 21. The transmission system of claim 15 wherein the planetsystem comprises the first planet gear in mesh with the first sunwheel,the second planet gear being separate from the first planet gear and inmesh with the second sunwheel, and the first and second planet gearsbeing coupled by an idler gear in mesh with both the first and secondplanet gears.
 22. The transmission system of claim 15 wherein the planetsystem comprises the first planet gear in mesh with the first sunwheel,and the second planet gear being in mesh with the second sunwheel andbeing coupled in the first planet gear by being in mesh with the firstplanet gear.
 23. The transmission system of claim 15 wherein theinvention the planet system comprises the first planet gear in mesh withthe first sunwheel, the second planet gear in mesh with the secondsunwheel, and an idler planet gear fixed onto the second planet gear forrotation with the second planet gear and the idler gear being in meshwith the first planet gear to thereby couple the first planet gear tothe second planet gear.
 24. A transmission system including: a dualsunwheel system including a first sunwheel provided on an output shaftfor supplying output rotary power, a second sunwheel, a planet systemhaving at least a first planet gear in mesh with the first sunwheel anda second planet gear in mesh with the second sunwheel, the first andsecond planet gears being coupled together, a cage for carrying theplanet system; input rotary power supply means for supplying inputrotary power to the dual sunwheel system; a first magnetic powderedclutch having a first component including a coil and a second componentincluding a brake element, the first component being coupled to the dualsunwheel system for controlling the drive ratio of the transmissionsystem or an input drive control, and the second component being coupledto the other of the dual sunwheel system or the input drive control; asecond magnetic powdered clutch having a first component including acoil and a second component including a brake element, the firstcomponent being coupled to either the dual sunwheel system or being heldfixed stationary, and the second component being coupled to the other ofthe dual sunwheel system or fixed stationary; and power supply means forsupplying power to the first and second magnetic powder clutches tocontrol the dual sunwheel system to thereby set the drive ratio of thetransmission system.
 25. The transmission system of claim 24 wherein theinput drive control comprises the input rotary power supply means sothat the input rotary power into the transmission drives the first orsecond component of the first magnetic clutch so that when the clutch isactivated the degree of slippage between the first and second componentis changed to cause the other of the first or second component to movewith a particular degree of slippage with respect to the first componentso as to control the dual sunwheel system to set the drive ratio of thetransmission, and wherein additional control is effected by operatingthe second magnetic clutch so as to cause the first or second componentof the second magnetic clutch to further control the dual sunwheelsystem to set the drive ratio of the transmission.
 26. The transmissionsystem of claim 24 wherein the first component or second component ofthe first and second magnetic clutches is connected to the secondsunwheel of the dual sunwheel system for controlling the drive ratio ofthe transmission.
 27. The transmission system of claim 26 wherein thesecond sunwheel includes a control shaft and the first or secondcomponent of the magnetic clutches is connected to the control shaft.28. The transmission system of claim 27 wherein the second component ofthe first and second magnetic clutches is connected to the controlshaft.
 29. The transmission system of claim 26 wherein the firstcomponent of the first magnetic clutch is connected to the cage forcarrying the planet system so that when the cage rotates, the firstcomponent of the first magnetic clutch rotates with the cage, and whenthe first magnetic clutch is operated to produce the desired degree ofslippage between the first and second components the second component iscaused to rotate in accordance with a degree of slippage of the firstmagnetic clutch.
 30. A transmission system including: a first sunwheel;an output connected to the first sunwheel for providing output rotarypower; a control sunwheel; a planet system including a planet cagehaving first and second planet gears, the first planet gear meshing withthe first sunwheel and the second planet gear meshing with the controlsunwheel; input supply means for supplying input to the planet cage sothat rotary power is transmitted from the cage via the first and secondplanet gears to the first sunwheel and therefore to the output; acontroller for: (a) receiving signals indicative of the rotary speed ofat least any two of the output, the control sunwheel and the inputsupply means, and for producing control signals based on the said atleast any two of the speeds of the output, the control sunwheel and theinput supply means, to enable a change in drive ratio in a forwarddirection of the transmission; and (b) producing a locking signal whenreverse motion of the transmission is required; a first progressivecontrol device for receiving the control signals from the controller tospeed up or slow down the control sunwheel between a stationarycondition of the sunwheel and a first rotary speed of the sunwheel tochange the drive ratio of the transmission; and a second control devicefor receiving the locking signal from the controller for locking thesunwheel to the input to increase the speed of rotation of the controlsunwheel to a speed above the first speed to thereby place thetransmission into reverse.
 31. The transmission system of claim 30wherein the first control device comprises a magnetic powder clutch. 32.The transmission system of claim 30 wherein the second control devicecomprises a cone clutch.
 33. The transmission system of claim 30 whereinthe sunwheel is provided on a control shaft and the control shaftcarries a gear which meshes with a gear coupled to an output of thefirst device and also with a gear coupled to an output of the secondcontrol device.
 34. The transmission system of claim 30 wherein thecontroller includes a processor for receiving signals indicative of thespeed of the input supply means and the speed of the output, switchingmeans connected to the processor for receiving output signals from theprocessor to switch the switching means on and off to produce controlsignals for application to the first progressive control device foractuating the first progressive control device to speed up or slow downthe control sunwheel.
 35. The transmission system of claim 34 whereinthe control signals comprise: a DC pulse signal for actuating the firstprogressive control device to lock the first progressive control deviceto the control sunwheel; a variable AC frequency signal for controllingthe first progressive control device to adjust the speed of the controlsunwheel to a speed less than the said first speed; and a variable pulsewidth AC signal for actuating the first progressive control device toenable the control device to control the speed of the control sunwheelfrom the said certain speed to the first speed.
 36. The transmissionsystem of claim 30 wherein the controller includes means for producing atransition AC/DC signal for transition of the control signal from the DCpulse signal to the AC variable frequency signal.
 37. A transmissionsystem including: a first sunwheel; an output connected to the firstsunwheel for providing output rotary power; a control sunwheel; a planetsystem including a planet cage having first and second planet gears, thefirst gear meshing with the first sunwheel and the second planet gearmeshing with the control sunwheel; input supply means for supplyinginput rotary power to the planet cage so the rotary power is transmittedfrom the cage via the first and second planet gears to the firstsunwheel and therefore to the output; a controller including speedindicating means for providing signals indicative of the rotary speed ofat least any two of the output, the control sunwheel and the inputsupply means, and for generating a control signal for controlling thedrive ratio of the transmission system; and a control mechanism forreceiving the control signal and for controlling the control sunwheel inaccordance with the control signal to thereby adjust the drive ratio ofthe transmission.
 38. The transmission system of claim 37 wherein thecontrol device includes a first progressive control device for receivingthe control signal from the controller to speed up or slow down thecontrol sunwheel to change the drive ratio of the transmission.
 39. Thetransmission system of claim 38 wherein a second control device, thecontroller also being for generating a locking signal indicative of therequirement for reverse gear, the second control device being forreceiving the locking signal and for causing the second control deviceto lock the control sunwheel to the input to increase the speed ofrotation of the control sunwheel to a speed above the first speed tothereby place the transmission into reverse gear.
 40. The transmissionsystem of claim 38 wherein the first control device comprises a magneticpowder clutch.
 41. The transmission system of claim 37 wherein thecontrol sunwheel is connected to a control shaft which comprises a firstcontrol shaft portion and a second separate control shaft portion, thefirst and second control shaft portions being coupled together by gears,the control mechanism being mounted on the second control shaft portion.42. The transmission system of claim 37 wherein the control device ismounted for rotation and is coupled to control shaft drive means forrotating the control mechanism.
 43. The transmission system of claim 42wherein the control shaft drive means comprises a gear system whichtransmits drive from the input to the control device.
 44. Thetransmission system of claim 43 wherein the gear system comprises a ringgear coupled to the cage, a pinion gear meshing with the ring gear, ashaft coupled to the pinion gear, a second pinion gear on the shaft, asecond ring gear having internal and external teeth, the second pinionmeshing with the internal teeth, and the external teeth meshing with agear coupled to the control device for rotating the control device. 45.The transmission system of claim 44 wherein the control device comprisesa magnetic powder clutch having an outer housing portion coupled to thefurther gear, and an inner section mounted on the second portion of thecontrol shaft, so that when the input is driven, the outer housing ofthe powder clutch is rotated by the gear system and when the powderclutch is activated, the inner section and second portion of the controlshaft is controlled in rotation, dependent on the control signalsupplied to the powder clutch to in turn control the rotation of thefirst portion of the control shaft and therefore the control sunwheel,to set the drive ratio of the transmission.
 46. The transmission systemof claim 41 wherein the second portion of the control shaft includes avariable centroid system having moveable masses which, upon rotation ofthe second portion of the control shaft, move rotary outwardly to slowdown rotation of the second portion of the control shaft and thereforethe first portion of the control shaft.
 47. The transmission system ofclaim 37 wherein the control device includes a first variator having atoroidal gear track having gear teeth which change in pitch from aninner diameter portion to an outer diameter portion, the first variatorbeing coupled to a variator drive mechanism for rotating the firstvariator, a second variator having a toroidal track having gear teethwhich change in pitch from an inner diameter portion to an outerdiameter portion, the second variator being connected to the controlshaft, a pitch transfer gear in mesh with the gear teeth of the firstvariator and the gear teeth of the second variator, means for rotatingthe pitch transfer gear so that the gear can engage at any portion alongthe variable pitch of the toroidal track of the first variator and thetoroidal track of the second variator to thereby set a drive ratiobetween the first and second variators, and a driver for setting theorientation of the pitch transfer gear.
 48. The transmission system ofclaim 47 wherein the variator drive system comprises a gear system fortransmitting drive from the input cage to the first variator.
 49. Thetransmission system of claim 47 wherein the control shaft comprises afirst control shaft portion and a second control shaft portion, a pairof gears for coupling the first control shaft portion to the secondcontrol shaft portion, the first variator being rotatable relative tothe second control shaft portion and the second variator being mountedon the second control shaft portion for rotating the second controlshaft portion so that the second control shaft portion and therefore thefirst control shaft portion is controlled in rotation, dependent on thegear ratio set by the pitch transfer gear.
 50. The transmission systemof claim 47 wherein the orientation of the pitch transfer gear is set bya stepper motor and the stepper motor receives the control signal toactivate the stepper motor to rotate the stepper motor to in turn changethe position of the pitch transfer gear to control the rotation of thecontrol shaft and therefore the control sunwheel.
 51. A controller forcontrolling a ratio control device for setting a drive ratio of atransmission, said controller including: a processor for receivingsignals indicative of the speed of an input supply means and the speedof an output; switching means connected to the processor for receivingoutput signals from the processor to switch the switching means on andoff to produce control signals for controlling the drive ratio of thetransmission; and wherein the control signals comprise: a DC pulsesignal for actuating a control device and for placing the control devicein a locked condition; and a variable AC frequency signal forcontrolling the control device to adjust the drive ratio between a firstvalue and a second value; and a variable pulse width AC signal foractuating the control device to produce a drive ratio outside the rangebetween the first and second values.
 52. A transmission systemincluding: a dual sunwheel system having a first sunwheel and a secondsunwheel, the first sunwheel providing output rotary power when thetransmission system is operating; a planet system including a firstplanet gear and a second planet gear coupled to the first planet gear,the first planet gear meshing with the first sun gear and the secondplanet gear meshing with the second sun gear; a cage for carrying theplanet system; input means for receiving input power from an input powersource and supplying the input power to the dual sunwheel system tocause the dual sunwheel system to supply rotary power at the firstsunwheel; control means for controlling the dual sunwheel system so asto set the drive ratio of the transmission by causing the first sunwheelto advance or regress relative to the input means by displacing momentumback and forth between the first sunwheel which provides the outputrotary power and the control means; and wherein the control meansfurther includes speed monitoring means for providing signals indicativeof the rotary speed of at least any two of the output, the controlsunwheel and the input means, and for generating a control signal so thecontrol means can control the dual sunwheel system to set the driveratio of the transmission.